Almost certainly an incompatibility issue here between the Intel and the Belkin. Intel admit they have problems getting the Pro series to work correctly in all enviroments, Belkin on the other hand produce cheap and cheerful Wireless Router/Modems that for the main part are supplied to home users, they work well within the limits of there design but even so have niggling issues that appear to be worse than say Netgear or Dlink on the matter of compatablity, they are also very tender and prone to sudden failures, issues I believe are more related too the firmware than the hardware, they do however make equipment that works with other components supplied by Belkin, so a simple change out of the Laptops adpater for a Belkin one should solve the problem.
If you really do wish to retain the Intel adpater, Intel should be able to recommend a compatible WA for you,
Possible workarounds:
Turn off the encryption facility and the onboard Belkin firewall through the interface....192.168.2.1 (Please make sure your firewalls are running though and be aware that the local Fleas will try to use your connection).
observe the connections progress over a period of time, if a connection is established and remains stable, first turn the firewall back on again and check progress, if it remains connected and stable, ramp up the protection level till it fails to maintain or try placing the Laptop in the DMZ, (Not going to get into Port forwarding here).
if it does not maintain even then the problem is going to require replacement , I would not suggest junking the intel adpater though Belkin do make compatible equipment if you feel you would like to try this solution which will have been tested and will be compatible with the WA.
As for the encryption, again trial and error, turn it off, observe and if it maintains try a lower level of encryption, if it still will not maintain a connection then there is not a lot you can do other than replace either the WA or the adpater with same make equipment.