My friend has a problem with his celeron 566, he used to have an internal modem, when that failed, he upgraded the board to celeron 566 and is trying to use an external modem now, called something like Gesterure (28.8 k) or something like that. Anyway he has windows xp, and when he tries to connect to the internet it connects but instantly disconnects and says can't establish connection. The isp company says it is a driver problem or corruption of files.

What is the problem?
Where do i get the driver for the modem? (don't have disk)
How can i fix this problem?

Any suggestions would be great. Thanks in advance.

It does sound like a driver issue, try the manufacturers web site, if thats not available, do a search on google using as much info about the modem as possible and add the word drivers

IE: search: brand model drivers

Why bother? Try www.ebuyer.com For £15 he can get a brand new 56k external one. (or £6.50 for internal!)
Alternatively try these for drivers:
http://www.drivershq.com/main.asp
http://www.driverzone.com/