I have been using an installation of of 04.09.01 for about 3 months or so with no real issues. I was developing a new portal and had editted probably 5 or 6 pages without issue. I now get this error when I try and edit text in an HTML/TEXT module.

UserName: admin
ActiveTabID: 186
ActiveTabName: Plans
RawURL: /Providers/HtmlEditorProviders/Fck/FCKStyles.aspx?tabid=186
AbsoluteURL: /Providers/HtmlEditorProviders/Fck/FCKStyles.aspx
AbsoluteURLReferrer: http://www.b2cdesign.com/Providers/HtmlEditorProviders/Fck/FCKeditor/editor/fckeditor.html?InstanceName=dnn_ctr589_EditHTML_teContent_teContent&Toolbar=DNNDefault
UserAgent: Mozilla/4.0 (compatible; MSIE 7.0; Windows NT 5.1; .NET CLR 1.1.4322; .NET CLR 2.0.50727; .NET CLR 3.0.04506.30; .NET CLR 3.0.04506.648; .NET CLR 3.5.21022)
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: 45bee29e-b831-4fc3-8cad-b710e2312218
InnerException: Invalid file name for file monitoring: ''. Common reasons for failure include: - The filename is not a valid Win32 file name. - The filename is not an absolute path. - The filename contains wildcard characters. - The file specified is a directory. - Access denied.
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: System.Web.FileChangesMonitor.StartMonitoringPath
StackTrace:
Message: DotNetNuke.Services.Exceptions.PageLoadException: Invalid file name for file monitoring: ''. Common reasons for failure include: - The filename is not a valid Win32 file name. - The filename is not an absolute path. - The filename contains wildcard characters. - The file specified is a directory. - Access denied. ---> System.Web.HttpException: Invalid file name for file monitoring: ''. Common reasons for failure include: - The filename is not a valid Win32 file name. - The filename is not an absolute path. - The filename contains wildcard characters. - The file specified is a directory. - Access denied. at System.Web.FileChangesMonitor.StartMonitoringPath(String alias, FileChangeEventHandler callback, FileAttributesData& fad) at System.Web.Caching.CacheDependency.Init(Boolean isPublic, String[] filenamesArg, String[] cachekeysArg, CacheDependency dependency, DateTime utcStart) at System.Web.Caching.CacheDependency..ctor(String[] filenames) at DotNetNuke.HtmlEditor.FckHtmlEditorProvider.fckStyles.Page_Load(Object sender, EventArgs e) at System.Web.UI.Control.OnLoad(EventArgs e) at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) --- End of inner exception stack trace ---
 

It seems like it is having an issue with /Providers/HtmlEditorProviders/Fck/FCKStyles.aspx but what is weird is that it only effect certain pages. Other pages in the same portal I can bring up the editor just fine. I would would have though that if it was an access problem to the provider I would  see this across all pages. Has anyone seen this before or has any idea of whats going on.

Thanks