A) While I was using it. B) On a new install of windows 7.
Explorer crashed and I received the message:
"No mapping between account names security IDs was done"
When trying to open various programs (including windows explorer) I get the above error message.
What's more it would appear my user account has been deleted! I still have a folder in C:\Users\ but when I go to manage user accounts I have no profile picture (and I cannot add a new one), also I cannot "manage users". So I have no way of adding a new user account.
This happened yesterday and I used safe mode to make a new account. Today when starting "ASUS AI Suite" (a tool for general computer hardware control) the problem reoccurred. Clearly something is seriously wrong.
When this happened before I rebooted my PC and at the login screen there was no user to click on to login, only a blank "user name" and "password" field to fill in. I tried putting my username and password in but to no avail. (that's when I used safe mode to create a new user)
I've left my PC running this time to try and investigate what the problem is.
If no one has any advice for me I planning on going back to a system restore point just after installing the new operating system
If that doesn't work, then I'm looking at a clean install...
*I have not tried to rename or in any other way alter my user account
Running system restore gave a VSS error, so I'm running system restore from the boot menu, which seems to be working - yay
System restore worked, I'm now reinstalling stuff. Thanks for everyone's help! And I shall avoid using AI suite, I might try contacting ASUS about it, perhaps try and recreate what happened using a different user profile too.