I would say- check the settings in
the network control panel.
Is it using WEP ?
If so, you may want to make sure
there are dashes in the WEP key.

The WEP stuff would not lend itself to
intermittent connection dropouts though,
if you had the key wrong, you just
would not connect at all to the router.

If I had to guess, it sounds like you
possibly have some interference somewhere...