lapse of memory

I recently built a 1.6ghz P4 computer it has 512m of ddr ram, 60g Maxtor hard drive, a Lite-On DVD player and HP cd16 cd writer. I opted to load XP Home but now even with the bios and driver updates at times the computer will “forget” its display settings and a few times after loading programs during the execution of them they will simply stop without prompting to do so and further more it has at times revert to a time before programs were installed it would literally erase recently installed programs. the frustration would lie in resetting these attributes once the computer decides to “forget” them. I use SystemSuite 4.0 for the AV and firewall duties any help would be much appreciated thanks