Internet provider installation stuck

Hi I have been running XP with an Orange ADSL account without too many problems but yesterday I was trying to install their installation software on my other PC when halfwat through, we had a power outage (It happens a lot in rural France). After it was restored I tried a number of times to run the installation software again but got a message like " this installation is already running ". I have deleted all the "Orange" related files I can find but I still cannot run the installation. Any help would be useful.
TIA

 

stuck installation

Tried that and didn't make any difference. When I run the installation prog with Taskmanager running, it loade files called "Woohook ", "instcore" and "HSSRA" and then "Installgui.exe" flashes up for an instant then disappears and the programmes just stalls.
HELP!

 

installation stuck

After 2 days deleting files, trying to re-install then tryng the same in Safe Mode, It suddenly dawned on me this morning to try "System Restore" and that fixed the problem - I would still like to know how I could have recovered the situation had I not been able to use "System restore ".