The most common error is trying to test a folder that you do not have write permissions for (ie. Error creating test file...(53) File not found). Either changing permissions or choosing another folder is required. Be aware that there are certain folders that windows 7 won't let you create new files in (ie. c:\ or c:\program files) - even with admin rights.
Another error that is commonly seen is 'The Folder xxxx is not writable...If you want your settings saved you must have read/write access to this folder.' LAN Speed Test checks to make sure the LST_Settings.ini file (contains settings & registration info) is writeable (unless started in Command Line Mode). If it is not, you get this warning letting you know that settings will not be able to be saved.
Another common error is 'Error opening port: Error #57'. This usually means one of the following:
1) You have a firewall blocking the port of LST Server. Open port 4456 (or your custom LST Server port) on your LST Server's firewall
2) You have the incorrect ip address or port # of the computer running LST Server. Double check your IP address and port # of LST Server (shown on LST Server's screen) and correct on LAN Speed Test.
3) LST Server is not running on the computer to be tested with. If you do not have LST Server, what you want to do is click on the [...] button and select a shared folder from the server to test with. Now the 'Folder or Server IP:' box should contain something like 'F:\Public Files'
4) LAN Speed Test starts testing, but then pauses or does not finish correctly. This is usually caused by certain anti-virus engines. Try disabling the anti-virus software temporarily for testing. There are many anti-virus engines that affect your network speed considerably.