Sporadic Login issues after CF10 upgrade

Greetings

We recently upgraded from CF8 to 10- (IIS win 2008 R2)

We also recently moved the intranet from an older server to a virtual environment (VM ware).

Since these changes were made, quite a number of people who are trying to login to various apps across the organization are experiencing one or both of these issues:

1) they enter their UN & PW- it simply disappears and goes nowhere

2) they get  "request_uuid undefined in session" error

I have: <cfset Session.request_uuid=createUUID()> at many login  pages

Some are having the issue, some are not. All are using either IE 7 or 8, and 95% win 7. There is no evidence that the IE versions play any role in this.

There are 320 people in the org.

Any help would be greatly appreciated.

Norman