PC unresponsive unless in safe mode

Hi
I have a dell lnspiron 630 m. The machine is currently (mostly) unresponsive unless in safe mode. It sometimes seems ok but on reboot becomes unresponsive once again. I have made some changes suggested on your site including:
checking add remove programs for unwanted items (none existed)
run ATF Clean
run system clean (some viruses and worms were detected and removed unfortunately i did not note their names)
run CCleaner which repaired / removed some registry entries.
installed and run AVG 2008 - found one trojan and moved it to AVG prison (no option to delete)
Also manually found and deleted a file named file.exe
Most of this was run in safe mode.
I have downloaded all of the tools recommened by yourselves - mtools, superspyware, combo fix , antiMalWare etc - but I am stull unable to access the system in normal mode in order to run these applications.

ps also changed msconfig to set system boot normally.(was previously configured to boot selectively)

I notice that when the system starts up and begins to populate the desktop - there is a black/dos screen flashes for a brief time but I cannot capture the contents.

Any help appreciated

Jeannief