Problem with SL and Verizon wireless broadband

Here's an interesting problem I'm having with SL and my connection.

While I'm using second life on my PC after about 5 minutes (or sooner), my verizon wireless modem becomes "missing" for a few seconds (my PC sees it as not being connected anymore), causing me to become disconnected, as soon as I am disconnected from SL the PC recognizes it again and reconnects me to the internet.

*Using the same modem on my laptop the issue does not occur at all.
*This problem does not occur with any other online application on my PC (web browsing, WoW, chat programs, other misc multiplayer games online)
*I have contacted Verizon and they say the issue is most likely with an application utilizing my connection and not a hardware or connectivity issue

Specs:

PC:
Windows XP (SP1&2)
AMD 64 3200 CPU
2 gigs RAM
Radeon x1600 512MB RAM

Laptop:
Windows Vista (32bit home edition, no updates)
AMD 64x2
894MB RAM
ATI Radeon Xpress



On a (possibly) similar note, if I try to adjust my SL graphic settings in any way shape or form, SL crashes, so I'm stuck in the "Ultra" rendering mode

Dunno how much this will help, but have you tried port forwarding?

Also, have you tried changing your graphics settings from the login screen?
Just go Edit->Preferences before you log in.