Hi,
Unfortunately, the version of 6.86.9 (current one) can't work reliably on Virtual PC 7 (Mac OS X), virtualised windows (Sun solution) on Intel Mac.
6.84.x one, available from CNET Download.com works fine except it crashes the phone if one tries to Backup phone (my primary purpose was that)
While I verified the Virtual PC 7 (current) with XP SP3 myself, I also saw a bug report to Sun Microsystems supported regarding same error.
I thought it was some kind of timing issue since as you may guess, VPC runs really slow even on Quad (4x) G5 2500 but the report at Sun really made me think about something else.
There is something wrong with current cable drivers I think.
Check the bug reports at
http://www.virtualbox.org/ticket/470In fact, they may provide more insight than a "real" Windows running on PC.