Corel Draw X4 file saving problem...

i am having two system with corel draw installed on both of them...
1st being the slower P3 system at my home so i installed corel draw 12 on it and other being the fast one at my office is installed with corel draw X4....

Sometime for urgent work i bring my files for working on my home PC and the problem that rises is that sometimes i forget to save .cdr file with version 12 support.. so i am unable to open my files at my home that causes delay in my work... :mad:

So what i'm asking here is that is there a way by which i can make corel draw x4 to save files for version 12 by default i.e i do not have to select version 12 while saving files it gets automatically saved in version 12... :confused:

please help me out if there is anything that i can do (registry hack or anything else)... :(