Hi urzica,
I have written a small HTA app that will press the num-lock key twice in quick succession every n seconds. The same as if every n seconds, you then press num lock twice. This means that the computer will remain in the num-lock state it was in.
Copy the code below and save to a text file called KeepAlive.hta
Then run the hta file and enter the number of seconds for the interval for the program to press the num-lock key. I would suggest you use 600 (10 minutes). Then Click OK and minimize the program.
Hope this helps,
Daz.
P.S. tested on WinXP only.