Having problems logging in, here are some possible reasons and fixes.

1. Incorrect User Name.
You have to use your User name and not your Display name. These are two separate things. These are case sensitive and must be entered as shown.

2. Incorrect Password
Passwords are case sensitive and must be entered as shown.

3. Browser problem related to using Internet Explorer.
Internet Explorer has a known issue with UBB Threads, the software which powers SH. Because of this IE will randomly block your ability to log on, or stay logged on. If you find you cannot log on or you are being logged out try one of the following.
a. Add Sniper's Hide to your trusted sites in IE
b. Turn off Protection Mode

If none of the following appears to be working, the next step is to download and use Firefox and Chrome. Using these browser is a known fix for the problems associated to using Internet Explorer. Both Firefox & Chrome are free and work better with UBB Threads.

That is only a patch, it doesn't work at all for systems/businesses who are IE-only. Other software (ie: photopost) that will use the ubb cookie logs in without issues, so it's an issue that needs to be fixed with ubb.