PG 8 stop working !?

Hello,

I've a development workstation using Win XP Pro SP2 with PostgreSQL 8.1 win32.
This box use P4 3.2 Ghz, 1 Go RAM, 160 Go disk, no hardware problem detected.
>From several weeks PG seem to start (it appear as started in the services),
but when I want to use PG it hangs in the connexion (just after the password).
My PG config files are unchanged and where verificated.
I'm obliged to terminate psql ot pgAdmin III. All other applications works fine.
If I instal an other disk on that workstation with XP Pro SP2 and PG 8.1, it work fine.
There an hudge of programs and sources on that workstation, so erase the system partition
and réinstal all on that workstation would be an horror !!!
I tried to uninstall and reinstall (after boot) PG 8.1, I do an ugrade from 8.1.2 to 8.1.3
without success.
What should I do to repair my PG 8.1 on that workstation, how can I identify what goes wrong ?
I think that another software conflict with PG 8.1...
Best regards.

Luc