I dont know the adapter, so I dont know how well it performs, but unless it just cant get a good signal then a lot of times the problem is driver or firewall related.
What version is the driver that is installed for it? Are you using the windows built in wifi manager or the one that comes with linksys (I prefer windows built in one)
Also how is the signal strength?
It is also possible it is just a compatibility problem with the router, I have had that happen with some adapters and different routers, a lot of times a router firmware update will fix it as they fix the bugs in them, for others I had to use a different adapter, but once I replaced my router with a newer, better model all the adapters worked fine.
So as you can see it can be a number of things that can cause the same problem, so now begins the process of elimination.
Shane