admincp goes missing

I've just installed vbseo and I must say it looks great!
Unfortunately, the next time I went to my admincp and did a logon, I was redirected back to my site's index page.
Please note, I can get to admincp log in page, but once I enter my admin name and password and click login, I land up at site index page.
Modcp works fine, so far only admincp is having issues.

Any ideas?

Thanks.

PM sent.

This issue has been resolved by setting "File not found handler" to "Send 404 code" in vbseocp.