If your question pertains to a specific client that you've already been running successfully, please post in the topic associated with that client. (We may choose to move your post there anyway.)
Quoting from our Forum Policies
If you need help with some aspect of Folding@Home, especially when troubleshooting problems then please post the following details to help make things easier:
Computer Specs: Specifically CPU type and speed, RAM amount and number of CPU cores, especially. Don't forget your GPU type if you're folding with it.
Network Connection: Dialup? Cable? DSL? Via intranet? Any firewalls or proxy servers?
Operating System: Windows/Linux/BSD? What distro/version? Latest patches applied?
Overclocked?: What is overclocked? By how much?
Stable?: Try a few stability testing programs if you think that FaH is crashing your computer. It may be that your PC is just unstable overall.
Software: What version of the client are you using? Remember that Beta and prerelease versions can be unstable. What version of the core(s) are you using?
WU details: Gromacs, DGromacs, SMP, GPU? What WU? Run/Clone/Gen.
Also, when appropriate, please post the contents of fahlog.txt (V6 and earlier] or log.txt {V7]: this tells loads of information and is vital in helping to diagnose/troubleshoot problems.