WiFi causes extreme computer slowdown

I have a Precision M2400 as my primary work PC that I inherited when I started my new job at the beginning of the year. It has the Intel 5300AGN WiFi card. Since I have started, if I have the WiFi switch turned on while I'm connected using a wired connection, at least once a day the laptop will grind to a virtual halt. Opening up Task Manager reveals that taskmgr.exe itself is using nearly 100% of the CPU, and my choices are either shut down gracefully (which takes almost an hour) or hard power off (which makes me lose unsaved work). If I don't have the WiFi switch in the On position, this never happens. The WiFi is configured to automatically connect to my work wireless network, which is running on a Linksys wireless router. This hasn't happened offsite yet, but I also don't typically have my laptop on for more than a couple of hours if I'm at home or a branch office.

Also of note, when this happens I can't return to normal operation by simply turning the WiFi switch off. Nor will a warm reboot fix the problem. I have to power the laptop down completely and then power back on to fix the problem. I've checked for viruses, obviously, and updated my WiFi drivers. I know I can just turn my WiFi off when I'm in the office, but 1) I don't know if the problem is necessarily limited to in-office use, and 2) I use WiFi exclusively when I'm not in my office and I don't always remember. I have not tried reinstalling Windows yet, because this is my work PC and it would take me nearly a week to get back up and running with all the software I use here.

Has anyone ever encountered a problem like this, or have any suggestions for something else I can check or try?