Add-ons and themes don't work everytime I use FFP with different computers

FFP2.0.0.13, XP and Vista.

First, I installed FFP to my own computer. I was in rush so I didn't try to run the program at that time. Then, I tried to run the program on my work computer. It ran, but none of addons and themes are working properly. So, I reinstalled the program in different folder while keeping the original installation folder in the same drive. Then, I installed all addons and themes from scratch and it worked perfectly with my work computer. The story didn't end here.I tried to run the program on a computer in my school's lab, but none of extensions and themes work again!

I have found a post that said something about addons and absolute pass.
I'm assuming each computer gives different drive names to my Flash drive.
I tried to fix it myself but I don't knwo where I should put folders of add-ons and themes.
Could any of you tell me how to fix this?

thanks