Error during reindexing JIRA

The log file shows following error after starting a reindex in the adminsitration console of JIRA.

2006-12-08 10:13:14,884 http-8080-Processor21 ERROR [web.action.admin.IndexAdminImpl] Exception reindexing: com.atlassian.jira.issue.index.IndexException: com.atlassian.bonnie.LuceneException: java.io.IOException: Cannot delete C:\ELSTERonline\Data-su\JIRA37\index\issues_5e3.cfs
com.atlassian.jira.issue.index.IndexException: com.atlassian.bonnie.LuceneException: java.io.IOException: Cannot delete C:\ELSTERonline\Data-su\JIRA37\index\issues_5e3.cfs

The mentioned index file was indded not deleted and has an older modified date than all the other files: It has the date of JIRA application start.

The full error statement can be read in the attached log file.

cheers,
Alexander