When you do a restart, it merely reloads the operating system on most computers, without going through a full shutdown cycle and unloading all device drivers from memory, and it also does not run through the full bootup cycle. This may result in minor glitches if you have some poorly written drivers on your system, and some programs (especially graphics or image editing) will load special purpose drivers when windows starts which could be your problem. I always recommend that people do a full shutdown of their system before restarting, but when you install new software it often asks you merely to restart. What I do in this case is I let it restart, then after Windows is fully loaded, I do a full shutdown and restart. Because of this and the fact that I keep my computer very clean (in terms of software and registry) I have not had a system freeze or real problem of any kind for several months now (except the time I fried the motherboard, but that was unrelated to this.)
I hope this helps. I suggest you use a registry cleaner program like Microsoft RegClean (Which I can email you if you want) to regularly clean your registry, and sometime I might tell you a way to rebuild your registry but it's not for beginners to try.
Best regards.
PS, do you know what speed your proccessor is, i.e. is it a 450, 500, ect.?