[THIN] HP pavilion Laptop and Web client

I had case that has been frustrating me for a long time.  2 users have HP pavilion laptops ( I dont have hte exact model number) but they were running WinXP all patched up properly and no matter what I did they would never launch the Web plugin.  Even using File-mon to try and se the processes never yielded any clues.  There were no error messages, nothing in the event log, and no TSCAL issues.  The ICA file was associated with the Citrix Runtime, but  nothing would ever launch.  Out of Depseration I finally installed the Full PN and suddenly they started connecting like normal. WHile I am currently calling case closed, any idea why this is happening would be helpful.

I have had rare cases where I can tell there are no licensing issues, the client installs, the file associations look good, but when you try to launch the ICA file either from within WI or saved to desktop and launched manually never even shows that its attempting to connect.  Again there are no error messages anywhere I can find and file association looks good.  This is happenign with one other individual currently, he is not on a pavalion.  I have installed the Full PN and still ge the same result.