A problem saving maps on the Srb2 Doom Builder

Recently I've been having problems saving my maps on the Srb2 Doom Builder. More specifically this one:

Error 5 while saving map: Invalid procedure call or argument

My OS is Windows Vista Home Premium (64-bit operating system), and from what I've read, I see that this kind of problem usually relates to my OS. I'm not exactly sure how to fix this, or if this problem is even able to be fixed. If anyone is able to help me with this problem I'd appreciate it.

Otherwise I'd like to know if there are any suitable substitutes for the Srb2 Doom Builder. Any in particular that are Vista friendly and by that I mean those that don't cause as much problems with Windows Vista. Again any guidance is appreciated.

You need to run it with administrative privileges (or else install it somewhere that you can write to with standard privileges).

Ah I see. Maps are saving properly, but I am not able to open maps that didn't save properly when this problem was occuring. Anyways thanks for the help.

EDIT: I no longer have trouble saving maps but now I have a problem testing them. The Srb2 Doom Builder asks me to repeatedly direct it to the IWAD everytime I open my maps. That and everytime I try testing the maps it gives me an error saying that the IWAD can't be found in the right folder even though I directed it to the right folder right at the beginning. This is becoming increasingly annoying. Again any help is appreciated.