Connectivity Issue with Dell Inspiron 9100 Truemobile 1400 dual bank wlan mini-pci card

I am hoping someone can give me some pointers.  I have Linksys Wireless-G cable gateway.  My wireless card randomly kicks itself off.  I have to manually reconnect to the network and it will be fine again.  Sometimes I can browse a short while, but I cannot seem to browse through but a few minutes and then the card shuts down.  Any ideas as to what the problem is?  I am sitting only a few feet away from the Linksys and I have another laptop that can connect with no problems at all.  It seems to be an issue with my Truemobile 1400.  Help!?