Original post by: DrGlowire ,
More information about what kind of PC (brand, model) and the operating system would help. Some computers have built in diagnostics that you access when the computer first turns on. Diagnostics could show what parts are failing, although built in diagnostics range from simple to exhaustive testing. Some problems may be caused by software. The things to look for include bad memory, bad hard drive and bad motherboard. Bad memory will drop part of the information as it is moved from hard drive to processor back to hard drive, an intermittent problem would make this information loss harder to detect. Bad hard drive may have bad blocks that coincidentally happen in the middle of vital data or drivers. Bad mother board could have failing components that stop working, Ethernet port is one and other input/output devices are another. The power supply is probably good, a bad power supply would show up as unexpected shutdown or complete failure. This is just generic troubleshooting, a better diagnosis can be made if you can provide the model and manufacturer of the PC as well as which operating system you are using. Include more details about the problems and if you get any error messages or beep codes.