So, just some background - this root exploit works by basically copying a bunch of files onto your phone and then running them. The way it does this is with a free program called Android Debug Bridge, which is what "adb" stands for. On Windows, adb requires that you have the appropriate drives installed which are compatible with your phone, and the phone itself has to be set configured to allow the adb program to talk to it. On the phone, that setting is:
Settings->Applications->Development->USB Debugging (checked)
After you have the phone setup that way, and you've connected your phone, you need to make sure that adb is capable of talking to your phone.
The root exploit itself comes with a tiny version of adb and associated libraries; if you go into the command prompt and type "adb shell" you should see something that looks like a dollar sign ($). You can then type linux-like commands like "ls" and "exit". If you are unable to do those things, then the whole run.bat won't work because it depends on adb to be able to run commands on your phone.
If you can't get adb to work, it's most likely that the drivers you have are not working for your phone.
FYI, I did this on a Macintosh by running each of the adb commands in run.bat by hand; the Mac has the drivers built-in which are compatible with the LG Optimus Slider, so if you have access to someone's Mac you might want to try that there. There is also adb for linux, and that might be easier if you prefer doing it that way.