ERROR "security token was missing"

[Hades_uk]

Hi peeps,

Well recently our ISP had an outtage, but since it's all come back online we've had nothing but problems. 1st of all no-one could upload files to the server from the local PC.
But today no-one can even post, we also can't login unless the cookie is stored on your PC.
No-one can get onto Admincp. All with the same error.

Your submission could not be processed because a security token was missing

Now I've read lots of places this happened after an upgrade due to peoples templates and the CSRF. But our VB hadn't been upgraded, it was running VB 3.7.2 PL2.

Today I have tried upgrading like normal which was successful (no errors)

But still getting the "Security Token Is Missing" error.

I have read every bit of documentation I can find on the problem but none seem to help.

Help

Hades