Problem when moving tasks in Rapid-Board

Dear Madame or Sir,

we have the following problem when creating/moving tasks.
There is a workflow having different states in "Canban" for the allocation of tickets. Sometimes we experience the strange effect, that tasks having a state somewhere in the middle of the workflow and being moved to the succeding state are placed in the column for the initial state.
Executing a re-indexing , the task can be seen back in the correct state.

The Log shows the following entry:

2011-12-14 14:29:14,146 TP-Processor14 ERROR dschmidt 869x134889x1 xgmohe 192.168.0.72 /secure/QuickCreateIssue.jspa [groovy.canned.utils.WorkflowUtils] Not attmpting transition
2011-12-14 14:29:14,225 TP-Processor14 ERROR dschmidt 869x134889x1 xgmohe 192.168.0.72 /secure/QuickCreateIssue.jspa [velocity] Left side ($!

{displayParameters.get('isFirstField')}) of '==' operation has null value. If a reference, it ma
y not be in the context. Operation not possible. templates/jira/issue/field/worklog-edit.vm [line 2, column 62]
2011-12-14 14:29:14,225 TP-Processor14 ERROR dschmidt 869x134889x1 xgmohe 192.168.0.72 /secure/QuickCreateIssue.jspa [velocity] Left side ($!{displayParameters.get('isLastField')}) of '==' operation has null value. If a reference, it may
not be in the context. Operation not possible. templates/jira/issue/field/worklog-edit.vm [line 2, column 140]
2011-12-14 14:38:05,593 TP-Processor50 ERROR abeyreuther 878x134909x1 y4hef1 192.168.0.31 /secure/QuickEditIssue!default.jspa [velocity] Left side ($!{displayParameters.get('isFirstField')}

) of '==' operation has null value. If a referen
ce, it may not be in the context. Operation not possible. templates/jira/issue/field/worklog-edit.vm [line 2, column 62]
2011-12-14 14:38:05,593 TP-Processor50 ERROR abeyreuther 878x134909x1 y4hef1 192.168.0.31 /secure/QuickEditIssue!default.jspa [velocity] Left side ($!

{displayParameters.get('isLastField')}) of '==' operation has null value. If a referenc
e, it may not be in the context. Operation not possible. templates/jira/issue/field/worklog-edit.vm [line 2, column 140]
2011-12-14 14:38:29,617 TP-Processor41 ERROR dschmidt 878x134942x1 xgmohe 192.168.0.72 /secure/QuickCreateIssue.jspa [velocity] Left side ($!{displayParameters.get('isFirstField')}) of '==' operation has null value. If a reference, it ma
y not be in the context. Operation not possible. templates/jira/issue/field/worklog-edit.vm [line 2, column 62]
2011-12-14 14:38:29,617 TP-Processor41 ERROR dschmidt 878x134942x1 xgmohe 192.168.0.72 /secure/QuickCreateIssue.jspa [velocity] Left side ($!{displayParameters.get('isLastField')}

) of '==' operation has null value. If a reference, it may
not be in the context. Operation not possible. templates/jira/issue/field/worklog-edit.vm [line 2, column 140]
2011-12-14 14:42:46,982 Thread-15 WARN [jira.plugin.common.CalendarProvider] Cannot get calendars: Cannot get login credentials.
sk.eea.alloct.remote.exception.ClientException: Cannot get login credentials.
at sk.eea.jira.util.AllocClientProvider.<init>(AllocClientProvider.java:32)
at sk.eea.jira.util.AllocClientProvider.getInstance(AllocClientProvider.java:44)
at sk.eea.jira.plugin.common.CalendarProvider.updateCalendars(CalendarProvider.java:52)
at sk.eea.jira.plugin.common.CalendarProvider.access$000(CalendarProvider.java:23)
at sk.eea.jira.plugin.common.CalendarProvider$1.run(CalendarProvider.java:36)
at java.lang.Thread.run(Unknown Source)
2011-12-14 14:43:01,587 TP-Processor22 ERROR dschmidt 883x135116x1 xgmohe 192.168.0.72 /secure/QuickCreateIssue.jspa [velocity] Left side ($!

{displayParameters.get('isFirstField')}

) of '==' operation has null value. If a reference, it ma
y not be in the context. Operation not possible. templates/jira/issue/field/worklog-edit.vm [line 2, column 62]
2011-12-14 14:43:01,587 TP-Processor22 ERROR dschmidt 883x135116x1 xgmohe 192.168.0.72 /secure/QuickCreateIssue.jspa [velocity] Left side ($!

{displayParameters.get('isLastField')}

) of '==' operation has null value. If a reference, it may
not be in the context. Operation not possible. templates/jira/issue/field/worklog-edit.vm [line 2, column 140]
2011-12-14 14:47:47,464 TP-Processor30 INFO tgramann 887x135372x1 2xlsgm 192.168.0.248 /secure/admin/workflows/PublishDraftWorkflow.jspa [atlassian.jira.workflow.OSWorkflowManager] User 'tgramann' updated workflow 'evolver Arbeitsablauf'
at 'Wed Dec 14 14:47:47 CET 2011'
2011-12-14 14:47:53,897 JiraTaskExectionThread-55 INFO tgramann 887x135375x1 2xlsgm 192.168.0.248 /secure/admin/IndexReIndex.jspa [action.admin.index.IndexAdminImpl] Re-indexing started
2011-12-14 14:47:53,897 JiraTaskExectionThread-55 INFO tgramann 887x135375x1 2xlsgm 192.168.0.248 /secure/admin/IndexReIndex.jspa [jira.util.index.IndexLifecycleManager$Composite] Reindex All starting...
2011-12-14 14:47:53,897 JiraTaskExectionThread-55 INFO tgramann 887x135375x1 2xlsgm 192.168.0.248 /secure/admin/IndexReIndex.jspa [action.admin.index.IndexAdminImpl] Re-indexing is 0% complete. Current index: Issue
2011-12-14 14:47:53,897 JiraTaskExectionThread-55 INFO tgramann 887x135375x1 2xlsgm 192.168.0.248 /secure/admin/IndexReIndex.jspa [jira.issue.index.DefaultIndexManager] Reindexing all issues