Error on a site with a lot of OpenContent modules

[EPTamminga]

Anybody a suggestion what could cause this:

The process cannot access the file XXXX....XXXX because it is being used by another process. OpenContent UrlRewriter

Message: The process cannot access the file 'www.xcess.nl\Portals\0-System\Cache\OpenContentUrlRules\0_E3B0C44298FC1C149AFBF4C8996FB92427AE41E4649B934CA495991B7852B855.data.resources' because it is being used by another process.

StackTrace:

   at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath)
   at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost)
   at System.IO.StreamWriter.CreateFile(String path, Boolean append, Boolean checkHost)
   at System.IO.StreamWriter..ctor(String path, Boolean append, Encoding encoding, Int32 bufferSize, Boolean checkHost)
   at System.IO.File.InternalWriteAllText(String path, String contents, Encoding encoding, Boolean checkHost)
   at Satrabel.OpenContent.Components.UrlRewriter.UrlRulesCaching.SetCache(Int32 portalId, String cacheKey, TimeSpan duration, List`1 rules)

[Timo-Breumelhof]

I checked some of our site that use a lot of Open Content and they don't have these kind of errors. Is there anything special in your environment, like virusscanner etc...?