Dell Dimension C521 - Processor Problems

I have recently bought a Dell C521.  It has the AMD Athlon(tm) 64 X2 Dual Core Processor 4400+, 2.30 GHz, 1GB RAM.  I have noticed some problems with working in IE and possibly other programs.  When I am streaming a video cast from a web site, it will stall for a few seconds.  In troubleshooting I noticed that the CPU utilization when to 0 at those times.  I turned the affinity (processor selection) for the IEXPLORE.EXE process to just one of the CPUs and I have a lot better operation.

 

I have had downloads that start well and then hang.  This appears to be random, and I cannot isolate it to anything else happening on my system.  It appears to me that there is some arbitration happening at a low level when the process is deciding which processor to use.  This appears to have some problems with the SW and will cause some to stall (video stream) or hang (download).  That is my best guess at this time.

 

Does anybody else have a similar experience or know what this sounds like?  Thanks!

 

Bill