One of the cores works at 100%

I was using yesterday my computer (Inspiron E1505) as usual at work, connecting to the company network (using a VPN connection), sudenly, the computer started work too slow, and on the gadget I saw one of the two cores was 95-100%, while the other one was at 2%... :smileysurprised:

I started looking on task manager for the programs using the biggest amount of CPU usage an memery as well, ended those processes, but the core 1 still at 100%. I even bring up the processes from other users (SYSTEM, NETWORK, LOCAL SERVICES, there are no other users on this computer) and I tried to finish some with a big amout of CPU usage. some of them, of cuorse were not able to be finished. After a long wait to see what the problem was, I decided to restart the computer, the computer worked fine for another 3-4 hours, and then, the same problem, I did, by accident, the Fn+F2 ( iwas going to do the Fn+F3 to check the battery) and the wireless connection was lost (as well the blutooth), surprise, the core1 whent immediately to 2%... And everything started to work normal, I re-enabled the wireless connection and I connected to the the network, and then to my VPN... Everything started working perfect... Since then I've had not the problem again... Any idea why the network connection was making the core1 to go to 95-100% of usage...???