SPFile.MoveTo Thicket Exception

I'm getting Thicket file exception on SPFile.MoveTo call. But I'm not processing htm or mht file or frontpage files. Is there any other case it throws below exception? 
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> Microsoft.SharePoint.SPException: You cannot copy or move a thicket file.  To change the file name or create a copy of the file, open the file and save as to a new name. ---> System.Runtime.InteropServices.COMException (0x800700D6): <nativehr>0x800700d6</nativehr><nativestack></nativestack>You cannot copy or move a thicket file.  To change the file name or create a copy of the file, open the file and save as to a new name.
   at Microsoft.SharePoint.Library.SPRequestInternalClass.MoveUrl(String bstrUrl, String bstrWebRelOldUrl, String bstrWebRelNewUrl, Int32 grf)
   at Microsoft.SharePoint.Library.SPRequest.MoveUrl(String bstrUrl, String bstrWebRelOldUrl, String bstrWebRelNewUrl, Int32 grf)
   --- End of inner exception stack trace ---
   at Microsoft.SharePoint.SPFile.MoveCopyInternal(String strNewUrl, Int32 grf, Boolean requireWebFilePermission)
   at Microsoft.SharePoint.SPFile.MoveTo(String newUrl, SPMoveOperations flags)

Bala