Combo Q:Net User cannot be found/ allow wireless..?

[ryoko]

Hey just learned how to tweak net user time format in cmd for Xp pro and its been a godsend to my situation and kids overusing computer.
All have their own login's I got one time set, but the other child changed their login name 2-3 times. I reset it back to the original name (from when I installed the os). Problem is when I try to set the time for the net user, it rejects the name saying user name could not be found, but when I command it to list the net users the name is correct. Is there any other cmd line or way to find out if the names changes are still listed somewhere preventing me to set the cmd line in that user?

Oh one other issue I wanted to set them as limited access but the wireless 802.11g cries out error messages upon their login and won't work- how can I set them to limited but allow them to use the wireless internet connection? (right now I have to set them as admin)
Thanks for your replies!