unrecognized command line option "-imultilib"?

Hello. Recently when trying to compile/upload code to my arduino duemilanove from the arduino 0018 editor, i receive these errors every time:

cc1: error: unrecognized command line option "-imultilib"

cc1: error: invalid option `mcu=atmega328p'

cc1: avr5: No such file or directory

It was working before on my laptop but never worked on any other computer, but now all i get is that error, what's the issue here? I haven't changed anything to my knowledge.