You might not have permission to use this network resource. Login failure

I tried the search below
http://www.google.com.au/search?hl=e...G=Search&meta=

But I was not able to solve my problem

I have got Desktop with XP Pro, and Laptop with XP Pro SP3.

On Desktop --> Run --> \\Laptop\C$ or D$,,,,,,,,,,,,,,,,,I have got no problem (hidden default administrative share)

On Laptop -> Run --> \\Desktop\C$ or E$ (hidden default administrative share), I had been presented with the below error message

Quote:

You might not have permission to use this network resource. Contact the administrator of this server to find out if you have access permission Login failure : the user has not been granted the requested logon type at this computer

1- No firewall on both PCs

2- Having same account and same passwords did not solve the problem.

3- "Simple file sharing" unticked from both PCs.

4- Laptop connected to a router wirelessy and Desktop is connected wired.

5- All of the sudden this problem happened, it was working before.

What else should I try to overcome this problem ?