I have a local area network of 4 computers. Two have wireless cards. All can access the internet with no problem. One wireless Sony laptop is the problem It can see all the computers and their shared drives but when any of the other computers attempt to access the Sony, they receive a message that "Sony is not accessable, etc". All computers are in the same workgroup, all are properly named, all have sharing set up correctly and there are no active firewall other than the internet connection. This problem occurred after resizing the partitions using Partition Magic. Doe anybody have a cure or encountered a similar problem after using Partition Magic?

This won't exactly fix your problem, but you can try to browse by their local IP instead of the computer name. Like \\192.168.x.x instead of \\sony. I would try that first as it is a temporary solution, but it should work nonetheless.

BTW
Welcome to TechSpot

Can you 'Ping' the Sony with it's IP addy? Also, have a look at your Sony's firewall log file (if you're running one) to see if it shows the other machines attempting to connect as port scans.