crystal report security/mscorlib problem?

[ireallyneedtoknow2007]

I have created a crystal report 10 using VS2005 and get the stack
trace/source exceptions below - SOMETIMES!, other times the report
works fine. The directory is always a grayed out Read-only - if I
uncheck it, it returns. ASP.NET is a user with full priviledges. VS
2003 reports worked fine. What else can I tell you to help figure
this out? I am stumped. Thanks.

StackTrace " at System.IO.__Error.WinIOError(Int32 errorCode, String
maybeFullPath)\r\n
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)\r\n at System.IO.FileStream..ctor(String path,
FileMode mode)\r\n
at
CrystalDecisions.CrystalReports.Engine.FormatEngine.WriteStreamToFile(Stream
stream, String filename)\r\n
at
CrystalDecisions.CrystalReports.Engine.FormatEngine.ExportStreamToFile(Stream
stream,
DiskFileDestinationOptions options)\r\n
at
CrystalDecisions.CrystalReports.Engine.FormatEngine.Export(ExportRequestContext
reqContext)\r\n
at CrystalDecisions.CrystalReports.Engine.FormatEngine.Export()\r\n
at CrystalDecisions.CrystalReports.Engine.ReportDocument.Export()\r\n

Source "mscorlib" string