Error in user administration / login invalid

Hi all,

Am implementing the internet sales scenario.

Configured the XCM etc, to support a b2b webshop.

was able to login via shop admin url - create shops, & also login via user admin url-create users etc.

However, when I tried to login to the b2b shop with the password that was generated in user admin- i got a mesg

"login is invaid-check ur entries". I was working on CRM 4.0 SP6.

I have now upgraded to SP8 a week ago,something seems to have gotten worse !!

now i cant even login via the user admin url- gives me a msg- "error in user administration, call our hotline".

I have checked for any red lights in su01- none at all.

I am able to login to the shop admin , but not user admin.

Any Advice /help ?????