Lost 3 WUs in a row

I've done 3 and lost 3... I posted the first error on here and the other two were bad checksum errors. Should I use 5.03 instead of 5.04 Beta? Is that what's causing these problems?
By the way it's running as a service now, with these arguments: -local -advmethods -verbosity 9
There was another one there (copied from goldfish's recommended list, the AMD dual core one) but it was conflicting so I removed it.
Do they cause instability?

 

Yeah I've recieved about 8WUs, completed 4 and only been able to successfully submit 2...
I completely uninstalled it and installed it again and it doesn't seem to be having any problems now though, very strange.
The errors were happening with the no nonsense client when it ran as either standalone or as a service, but that was 5.04 Beta instead of 5.03 so that might've been the problem. I'm just using the graphical client now 'cause I can't be bothered trying to get the others to work.
That EOC site is great too, thanks. Much better than the one I was looking at http://vspx27.stanford.edu/cgi-bin/main.py?qtype=userpage&username=SubJunk

So it looks like it's all sorted now, thanks

 

Oh one more thing. I think I read somewhere that you can have one instance running on each CPU if you have dual core, considering it doesn't support both CPUs at once. How do I tell each instance to run on a separate processor?

 

Ah yeah I found this article which is a great help http://www.short-media.com/review.php?r=293 Thanks