I have a computer on a domain that is getting the message "Document is not accessible. You might have permission to use this network resource. Contact the administrator of the server to find out if you have access permissions when trying to access" the "My Documents" folder on the network drive. This works fine but for some reason overnight, this one computer must lose the connection or something because the next morning it's like it is disconnected from the domain but it still has internet access, etc. Logging off the machine and logging back on fixes it.

Look in the account properties for the user. Is it set to allow logon during certain hours or is it allowed to have 24x7 access?

Look in the network configuration for the network card. There is a section that controls power save features for the network card. Make sure that the Power Management options are not set to turn off the network card to save power.

I have a computer on a domain that is getting the message "Document is not accessible. You might have permission to use this network resource. Contact the administrator of the server to find out if you have access permissions when trying to access" the "My Documents" folder on the network drive. This works fine but for some reason overnight, this one computer must lose the connection or something because the next morning it's like it is disconnected from the domain but it still has internet access, etc. Logging off of the machine and logging back on fixes it.
I am pretty sure I checked the power settings, and also the 24/7 on the user account, I'll have to travel to that office so it might be late this afternoon before I check, thanks.

Use Remote Desktop. Much better than traveling. And this is a machine setting and not a profile setting for the network card so you can set it under any user account.

Use Remote Desktop. Much better than traveling. And this is a machine setting and not a profile setting for the network card so you can set it under any user account.
I know that, I just took over the admin here and I have to configure the firewall there and the guy I am working for took 2 weeks off so I am still trying to get with the program as far as the network and all but I'm going down there later, thanks. I know networking, lol, just don't want to run everything by him for a while before I open things up.

Ouch... baled out on you. Not fair. Better you travel anyway in that situation.