Often after I connect to my office server through Windows XP VPN on my new 4g Verizon usb modem, Remote Desktop does not work, although it has worked a couple of times. Any tips?
How many bars do you get when you connect? Verizon 4G coverage is pretty spotty at best, and unless you live in one of the 20 or so places that it covers, you're probably getting 3G speeds.
If you are getting good reception, you might want to change the remote desktop settings to use less resources so there is less overhead. I'm afraid that because of the newness of the technology, the best thing you can do is wait until the network gets upgraded and you get more towers in your area.
Here is the map of coverage in case you're interested:
The green and yellow cirles are areas where 4g is supported.