big problem converting files

[semloh]

hi guys
my problem is that when i try to convert a certain avi file using tmpgenc, it says can not open or is unsupported,so i used mgi video wave 2 to convert it to avi again. is that the right way to go?
also when i do this it is very slow, it would take somewhere in the region of about 12+ hours to convert a 45 min file. is this normal? are there any faster software available?
i`m new to this so any help would be greatly appreciated.
thanks in advance

[Ceasar]

i get that prob. too m8 not sure what it is, as for the time it takes to encode its down to the quality u've selected and the speed of ur processor