Its a common problem that alot of people have..here you go...
Diablo II and Warcraft III Users:
Many customers have reported they could play the game, but after rebooting their machines, they received the "Please verify your CD is in the drive" error message. After reinstalling the game they could play but rebooting would create the problem all over again. You should not have to reinstall the game every time you want to play.
We have found a couple of programs that may be creating this problem. These programs include Kazaa and Kazaa Lite.
If you are experiencing this type of problem, please try uninstalling Kazaa, uninstall the game, reinstall the game, and then patch the game. Please note that removing Kazaa alone will not fix the problem - you need to reinstall the game after removing Kazaa. This solution may not work for everyone, but we have received many reports confirming this has helped.
My craptacular system spec's
AMD Athlon @1400mhz
Nvidia Geforce 3 Ti 200(Currently clocked at 250 Core and 550 RAM)
512MB Crucial DDR RAM
Thermalright Delta 68.6cfm fan
Ghetto Rigged Antec full tower case/self-installed Plexy glass with 120mm blue LED fan
300 watt power supply
Two 6 watt Altec Lansing wine glass speakers with a 18 watt 3' sub
Cordless Logitech Keyboard with a Logitech Infrared mouse
60gig Seagete hardrive
17" MAG Innovision Moniter
32x12x40 Lite-On Burner
OS = Windows XP Pro