You mention running this on a new computer. Any chance you've updated to Windows 8.1, 8, 7, Vista... and you're trying to run this out of Program Files?
By default, many of the back-end processes will fail if you do that, due to UAC. The two main choices you have are:
1) Put it somewhere where you have full control. On your desktop, in your downloads folder, in your User Profile folder, in your documents, wherever.
2) Grant 'Users' full rights to the KoLmafia folder, wherever it lives. Or at least Modify rights.
The BAD choice on how to make it work is to try to force it every time, either by trying to remember to run it through the command prompt as an Administrator each time, or setting compatibility settings which will get wiped out when you get a new version. Both of these are great ways to end up posting that stuff is broken at a later date and us running similar troubleshooting.
