SourceTree fails to start

after a few weeks of running just fine source tree refuses to start and fails nearly silently. the problem persists after rebooting and even reinstalling the software.

there are some errors in the windows event viewer:

Log Name: Application
Source: Windows Error Reporting
Date: 03/10/2013 09:51:05
Event ID: 1001
Task Category: None
Level: Information
Keywords: Classic
User: N/A
Computer: AM-SEMI
Description:
Fault bucket -402375852, type 5
Event Name: CLR20r3
Response: Not available
Cab Id: 0

Problem signature:
P1: sourcetree.exe
P2: 1.2.3.0
P3: 524414e5
P4: System.Xml
P5: 4.0.30319.18331
P6: 520a36ac
P7: 9b5
P8: 0
P9: IOIBMURHYNRXKW0ZXKYRVFN0BOYYUFOW
P10:

Attached files:
C:\Users\Semi\AppData\Local\Temp\WERC0DF.tmp.WERInternalMetadata.xml

These files may be available here:
C:\Users\Semi\AppData\Local\Microsoft\Windows\WER\ReportArchive\AppCrash_sourcetree.exe_2efd4f189b6ac395916eb725587d30e055c3ffe9_14e1c43b

Analysis symbol:
Rechecking for solution: 0
Report ID: ef2ec30f-2c08-11e3-be80-6c3be5219596
Report Status: 0
Hashed bucket: 40cc9a38b675c1b51a50f2a59637f8bb
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Windows Error Reporting" />
<EventID Qualifiers="0">1001</EventID>
<Level>4</Level>
<Task>0</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2013-10-03T08:51:05.000000000Z" />
<EventRecordID>11913</EventRecordID>
<Channel>Application</Channel>
<Computer>AM-SEMI</Computer>
<Security />
</System>
<EventData>
<Data>-402375852</Data>
<Data>5</Data>
<Data>CLR20r3</Data>
<Data>Not available</Data>
<Data>0</Data>
<Data>sourcetree.exe</Data>
<Data>1.2.3.0</Data>
<Data>524414e5</Data>
<Data>System.Xml</Data>
<Data>4.0.30319.18331</Data>
<Data>520a36ac</Data>
<Data>9b5</Data>
<Data>0</Data>
<Data>IOIBMURHYNRXKW0ZXKYRVFN0BOYYUFOW</Data>
<Data>
</Data>
<Data>
C:\Users\Semi\AppData\Local\Temp\WERC0DF.tmp.WERInternalMetadata.xml</Data>
<Data>C:\Users\Semi\AppData\Local\Microsoft\Windows\WER\ReportArchive\AppCrash_sourcetree.exe_2efd4f189b6ac395916eb725587d30e055c3ffe9_14e1c43b</Data>
<Data>
</Data>
<Data>0</Data>
<Data>ef2ec30f-2c08-11e3-be80-6c3be5219596</Data>
<Data>0</Data>
<Data>40cc9a38b675c1b51a50f2a59637f8bb</Data>
</EventData>
</Event>

Log Name: Application
Source: Application Error
Date: 03/10/2013 09:51:04
Event ID: 1000
Task Category: (100)
Level: Error
Keywords: Classic
User: N/A
Computer: AM-SEMI
Description:
Faulting application name: SourceTree.exe, version: 1.2.3.0, time stamp: 0x524414e5
Faulting module name: KERNELBASE.dll, version: 6.2.9200.16451, time stamp: 0x50988aa6
Exception code: 0xe0434352
Fault offset: 0x000000000003811c
Faulting process ID: 0x12c8
Faulting application start time: 0x01cec015b1606042
Faulting application path: C:\Program Files (x86)\Atlassian\SourceTree\SourceTree.exe
Faulting module path: C:\windows\system32\KERNELBASE.dll
Report ID: ef2ec30f-2c08-11e3-be80-6c3be5219596
Faulting package full name:
Faulting package-relative application ID:
Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name="Application Error" />
<EventID Qualifiers="0">1000</EventID>
<Level>2</Level>
<Task>100</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2013-10-03T08:51:04.000000000Z" />
<EventRecordID>11912</EventRecordID>
<Channel>Application</Channel>
<Computer>AM-SEMI</Computer>
<Security />
</System>
<EventData>
<Data>SourceTree.exe</Data>
<Data>1.2.3.0</Data>
<Data>524414e5</Data>
<Data>KERNELBASE.dll</Data>
<Data>6.2.9200.16451</Data>
<Data>50988aa6</Data>
<Data>e0434352</Data>
<Data>000000000003811c</Data>
<Data>12c8</Data>
<Data>01cec015b1606042</Data>
<Data>C:\Program Files (x86)\Atlassian\SourceTree\SourceTree.exe</Data>
<Data>C:\windows\system32\KERNELBASE.dll</Data>
<Data>ef2ec30f-2c08-11e3-be80-6c3be5219596</Data>
<Data>
</Data>
<Data>
</Data>
</EventData>
</Event>

Log Name: Application
Source: .NET Runtime
Date: 03/10/2013 09:51:04
Event ID: 1026
Task Category: None
Level: Error
Keywords: Classic
User: N/A
Computer: AM-SEMI
Description:
Application: SourceTree.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.Configuration.ConfigurationErrorsException
Stack:
at System.Configuration.BaseConfigurationRecord.GetSectionRecursive(System.String, Boolean, Boolean, Boolean, Boolean, System.Object ByRef, System.Object ByRef)
at System.Configuration.BaseConfigurationRecord.GetSection(System.String)
at System.Configuration.ConfigurationManager.GetSection(System.String)
at System.Configuration.ClientSettingsStore.ReadSettings(System.String, Boolean)
at System.Configuration.LocalFileSettingsProvider.GetPropertyValues(System.Configuration.SettingsContext, System.Configuration.SettingsPropertyCollection)
at System.Configuration.SettingsBase.GetPropertiesFromProvider(System.Configuration.SettingsProvider)
at System.Configuration.SettingsBase.GetPropertyValueByName(System.String)
at System.Configuration.SettingsBase.get_Item(System.String)
at System.Configuration.ApplicationSettingsBase.GetPropertyValue(System.String)
at System.Configuration.ApplicationSettingsBase.get_Item(System.String)
at SourceTree.App..ctor()
at SourceTree.App.Main()

Event Xml:
<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">
<System>
<Provider Name=".NET Runtime" />
<EventID Qualifiers="0">1026</EventID>
<Level>2</Level>
<Task>0</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime="2013-10-03T08:51:04.000000000Z" />
<EventRecordID>11911</EventRecordID>
<Channel>Application</Channel>
<Computer>AM-SEMI</Computer>
<Security />
</System>
<EventData>
<Data>Application: SourceTree.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.Configuration.ConfigurationErrorsException
Stack:
at System.Configuration.BaseConfigurationRecord.GetSectionRecursive(System.String, Boolean, Boolean, Boolean, Boolean, System.Object ByRef, System.Object ByRef)
at System.Configuration.BaseConfigurationRecord.GetSection(System.String)
at System.Configuration.ConfigurationManager.GetSection(System.String)
at System.Configuration.ClientSettingsStore.ReadSettings(System.String, Boolean)
at System.Configuration.LocalFileSettingsProvider.GetPropertyValues(System.Configuration.SettingsContext, System.Configuration.SettingsPropertyCollection)
at System.Configuration.SettingsBase.GetPropertiesFromProvider(System.Configuration.SettingsProvider)
at System.Configuration.SettingsBase.GetPropertyValueByName(System.String)
at System.Configuration.SettingsBase.get_Item(System.String)
at System.Configuration.ApplicationSettingsBase.GetPropertyValue(System.String)
at System.Configuration.ApplicationSettingsBase.get_Item(System.String)
at SourceTree.App..ctor()
at SourceTree.App.Main()
</Data>
</EventData>
</Event>