MAJOR PROBLEM: references to controls not recognized! name not declared!

HELP!!! All of a sudden all my references to web controls dont work anymore!
I have a login.aspx and a login.aspx.vb and when I refer to the textbox control tbName.Text from my .vb
file I receive the error: Name 'tbName' is not declared. I have absolutely NO idea how and why, it just suddenly happened!!

Try moving in Design view and then go to html source

Later see in code behind if you have those controls declared

Thanks! that worked...but thats a pretty anoying bug isnt it?!? or is there another problem?

Patel's suggestion of going into design view and back would normally work. But I am using nested master page and as a result, I cannot switch to design view. So this problem cannot be solved!

btw, this problem happens sometimes but not all the time, but it is very annoying and wastes me a lot of time. Any other suggestions?

Frank