system
6
I had the same problem, few weeks ago, after I installed XP Pro on one of my PCs.
As far as i remember :-\ I solved it this way:
First I followed the following path,
Start → Control Panel → Add or Remove Programs → Add/Remove Windows Components (left panel) → Internet Information Services (IIS) → details
Then I disabled a line having (SMTP).
The conflict at port 25 disappeared and the error message didn’t pop-up 
I read that the disabled service is not important and also uses port 25 (for debugging… using inetinfo.exe)
Kerim