can't log in into the system

[DimaT]

I have PC with IDE DVD- master, 40G IDE HDD, master, 2 SATA HDD. I tried to install ubuntu v8.04 (both clean install or through Wubi - same problem). It installs OK, but during first boot after installation it asked for user name and pass. I entered u/n and pass I set up earlier. Seems like it was thinking for several seconds, changed a mouse and returned to the same login screen. If I enter incorect pass/username it just says "incorrect username/password". But if it is correct one it is thinking for a little while and returns to the same boot screen. Please, help!

[Pumalite]

Burn a new CD. Follow this guide:
https://help.ubuntu.com/community/BurningIsoHowto?highlight=%28burn%29%7C%28
Do md5sum, burn at 4x or less on good quality CD-R, check CD integrity before install.

[DimaT]

The CD is OK (actually Wubi does check it). And it does install it to the HDD. I can't log in AFTER the installation on the hard drive.