Still encountering the delays.  The site is in a web farm environment and has been moved from another server group.  I'm going to try an installation from scratch and see if I get different behaviour.  Thank you very  much for taking the time to respond.  I think that I might have a complex problem that I can't resolve from a single setting.

Interesting, I just got this for the very first time with the new wiki module/test install of 4.5.1. I had only just installed the Wiki and within a few minutes of using it the below error message happened.It's working now, but issue might come back (only played with it for 5 minutes).....

>because it is being used by another process

Do you reckon it's possible for DNN to find out was this process is, would this be a useful enhancement?

AssemblyVersion: 04.05.01
PortalID: -1
PortalName:
UserID: -1
UserName:
ActiveTabID: -1
ActiveTabName:
RawURL: /Wiki/tabid/57/ctl/Module/ModuleId/381/Default.aspx
AbsoluteURL: /Default.aspx
AbsoluteURLReferrer:
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)
DefaultDataProvider: DotNetNuke.Data.SqlDataProvider, DotNetNuke.SqlDataProvider
ExceptionGUID: da22f21f-087c-4be0-b409-e7a026091898
InnerException: Unhandled Error:
FileName:
FileLineNumber: 0
FileColumnNumber: 0
Method: System.IO.__Error.WinIOError
StackTrace:
Message: System.Exception: Unhandled Error: ---> System.IO.IOException: The process cannot access the file 'D:\Data\websites\Test\Testdnn451\Website\Portals\_default\Cache\UG9ydGFsMA==.resources' because it is being used by another process. at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) at System.IO.File.Delete(String path) at DotNetNuke.Services.Cache.FileBasedCachingProvider.FBCachingProvider.DeleteCacheFile(String FileName) in D:\Data\websites\Test\Testdnn451\Library\Providers\CachingProviders\FileBasedCachingProvider\FileBasedCachingProvider.vb:line 298 at DotNetNuke.Services.Cache.FileBasedCachingProvider.FBCachingProvider.GetPersistentCacheItem(String CacheKey, Type objType) in D:\Data\websites\Test\Testdnn451\Library\Providers\CachingProviders\FileBasedCachingProvider\FileBasedCachingProvider.vb:line 97 at DotNetNuke.Common.Utilities.DataCache.GetPersistentCacheItem(String CacheKey, Type objType) in D:\Data\websites\Test\Testdnn451\Library\Components\Providers\Caching\DataCache.vb:line 191 at DotNetNuke.Entities.Portals.PortalController.GetPortal(Int32 PortalId) in D:\Data\websites\Test\Testdnn451\Library\Components\Portal\PortalController.vb:line 1410 at DotNetNuke.Entities.Tabs.TabInfo.get_IsAdminTab() in D:\Data\websites\Test\Testdnn451\Library\Components\Tabs\TabInfo.vb:line 435 at DotNetNuke.Entities.Portals.PortalSettings.GetPortalSettings(Int32 TabId, PortalAliasInfo objPortalAliasInfo) in D:\Data\websites\Test\Testdnn451\Library\Components\Portal\PortalSettings.vb:line 703 at DotNetNuke.Entities.Portals.PortalSettings..ctor(Int32 tabId, PortalAliasInfo objPortalAliasInfo) in D:\Data\websites\Test\Testdnn451\Library\Components\Portal\PortalSettings.vb:line 530 at DotNetNuke.HttpModules.UrlRewriteModule.OnBeginRequest(Object s, EventArgs e) in D:\Data\websites\Test\Testdnn451\Library\HttpModules\UrlRewrite\UrlRewriteModule.vb:line 319 at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) --- End of inner exception stack trace ---