For some reason, when My friend inserts a Blank CD-RW into his computer, his computer freezes, and when we eject the cd, the computer goes back to normal, what could be the cause of this?

Try multiple Cd's. perhaps the drivers are wrong, is this a new Cd drive? or maybe itc just time to get a new one.

It could be the actual media (the cd itself) alot of cd-r/rw companys sell faulty discs so you have to be careful. I doubt that would directly effect the computer in that way tho. I would say make sure you have a decent burning rom(nero for example) and make sure it is a version that is compatible with your OS (service pack 1 or 2 in the case of Windows XP). But the chances of that being the problem when it locks up directly on inserting the disc is slim to none. Did he just install the drive and it didnt work or has it worked before and just started doing that. If he just installed it you would want to make sure your drivers are the right ones and that they are compatible with the OS or possibly reinstalling them. If that doesnt work you might be better off taking it back and maybe having them test it. Or testing it yourself on another comp.

If he happens to be running Windows ME with this setup of drives or something similar (it is a common setup because it is for fast copying.

Primary IDE - hard disk drive as master

Primary IDE - a DVD-ROM drive as slave

Secondary IDE - hard disk drive as master

Secondary IDE - a CD-RW drive as slave

If this happens to be the case, first of all in add/remove programs uninstall every program that would possibly use the cd drive (itunes, music match, media player etc)
But leave one program that are for burning cds like nero and get rid of any others. If that doesnt work. Restart the comp in safemode (f8 or ctrl when restarting) and go into device manager once your in windows and remove all cd rom drives, then restart regularly and windows should automatically reinstall them.

uhh, if you somehow have a similar setup to that and none of that works I can post more possibilitys.

it suddenly began, and he gave me one of his cd's and In my computer works fine. He has Windows 98 second edition, with the original drivers and uses Nero burning room.

Everytime he inserts a Blank cd it frezes. But when he inserts a Music cd or a CD-RW recorded cd it works. it only happens with Blanks cd's

That is a common problem, exactly how you said it, blank cds lock the comp up, music cds work fine. I would say do a system restore but win 98 isnt capable. If he installed any new programs like music match or itunes you should try uninstalling them through add/remove programs (this is important because you need to remove the registry values aswell). The problem has to do with a program or registry value accessing the blank cd when its not supposed to I believe. Also you could try turning off "auto insters notification" on the drive. You might find it in device manager under settings. Check for any firmware updates by the roms manufacturer. Try a different brand of cd-rom if he just got a new set of cds that it is doing this with. Lastly you could check to make sure the BIOS file is the latest by downloading the latest one from the motherboard manufacturer's site.

My best guessw was driversl, but now that you mention it, the safty lock problem is probebly what it is, I dont know the exact base configurations for windows 98 when it comes to CD safty, if need be I can ask around or look it up but I think our 4saken brother has the problem handed..with style I may add.