Sharepoint - Cannot access document library files when logged in - sharepoint-2007

Question

I'm working on website where Sharepoint 2007 is being used as the CMS for a public facing site.
Internal users are authenticated via active directory and can edit content via an internal url. External users view the content via a public url. I've just added forms based authentication to the external facing version of the site in order to provide some special services to authenticated users.
The functionality works as expected on their dev servers but when rolled out to the test server any users authenticated via the forms based authentication are no longer able to access css files (which can be accessed via anonymous users). So all styling is lost. The CSS files are maintained in a document library. If the user is logged out these files become available again. (all via the external url and forms based authentication)
Any idea what might be going on?
Looking in the event logs provides the following information:
Event code: 3005
Event message: An unhandled exception has occurred.
Event time: 26/10/2010 3:08:20 p.m.
Event time (UTC): 26/10/2010 2:08:20 a.m.
Event ID: f6fbeb6ffe334e48aa150bc7d34aeda8
Event sequence: 159
Event occurrence: 29
Event detail code: 0
Application information:
Application domain: /LM/W3SVC/1334941635/ROOT-1-129325324099898564
Trust level: WSS_Minimal
Application Virtual Path: /
Application Path: E:\WebSites\test.company.co.nz\
Machine name: INTERNETTEST
Process information:
Process ID: 7616
Process name: w3wp.exe
Account name: CH\InternetTestAPESite
Exception information:
Exception type: FileNotFoundException
Exception message: The site with the id 5b06fc07-8611-4774-a283-7b9f94318030 could not be found.
Request information:
Request URL: http://internettest.company.co.nz/Style Library/Company/CSS/base.css
Request path: /Style Library/Company/CSS/base.css
User host address: 172.23.4.119
User: gavin.harriss#somecompany.co.nz
Is authenticated: True
Authentication Type: Forms
Thread account name: CH\InternetTestAPESite
Thread information:
Thread ID: 19
Thread account name: CH\InternetTestAPESite
Is impersonating: True
Stack trace: at Microsoft.SharePoint.SPSite..ctor(Guid id, SPFarm farm, SPUrlZone zone, SPUserToken userToken)
at Microsoft.SharePoint.SPSite..ctor(Guid id)
at Microsoft.SharePoint.Publishing.BlobCache.<>c__DisplayClass3.<EnsureAuthenticatedRights>b__0()
at Microsoft.SharePoint.SPSecurity.CodeToRunElevatedWrapper(Object state)
at Microsoft.SharePoint.SPSecurity.<>c__DisplayClass4.<RunWithElevatedPrivileges>b__2()
at Microsoft.SharePoint.Utilities.SecurityContext.RunAsProcess(CodeToRunElevated secureCode)
at Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(WaitCallback secureCode, Object param)
at Microsoft.SharePoint.SPSecurity.RunWithElevatedPrivileges(CodeToRunElevated secureCode)
at Microsoft.SharePoint.Publishing.BlobCache.EnsureAuthenticatedRights(Guid siteID, Guid scopeID)
at Microsoft.SharePoint.Publishing.BlobCache.RewriteUrl(Object sender, EventArgs e)
at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

Answer 1

It was a blob caching issue. Clearing the cache followed by an iisreset resolved the issue.