Can't create TCP/IP socket (10106)

When I try to connect from the webbrowser, I get the error "could not
connect: Can't create TCP/IP socket (10106)".
 
I tried:
- ping localhost and ping 127.0.0.1 -> work.
- startup mysqld-nt.exe as service -> works.
- change startup settings in Mysql Administrator to "with enabled named
pipe" -> has no effect.
- connect as root user, connect without user settings -> has no effect;
 
Furthermore it is strange that on my other PC it works... (which is no use).
Differences are other XP version, no java installed (but I don't use JDBC to
connect or anything), maybe some PHP differences. I don't believe it has
anything to do with PHP, because everything else works..
 
Can anyone please help me?
 
Thanks a lot!!!
 
Best regards, Rachel.