BC30456: InitializeCulture is not a member of xxx

Lately I've been getting this error on one of my ASP.NET 2.0 web sites: BC30456: 'InitializeCulture' is not a member of xxx

I've been getting it intermittently, ie. sometimes the page works fine and sometimes all I get is this error. I've been troubleshooting it for awhile but it finally looks like I have gotten a grip on it, much thanks to this MSDN thread.

This is what worked for me:

• Deleted a "Backup" folder that I kept in Visual Studio (but never copied to my production Web Server). In the Backup folder I kept copies if various apsx pages. Apparently you should not have multiple aspx pages referencing the same code file.
• Deleted the Bin folder on the Web Server before copying a new precompiled version there. Turned out I had lots of outdated bin files on the Web Server.

I have not yet installed Visual Studio 2005 SP1 (Service Pack) maybe this is something that is also solved there.