Problem burning, all my files are coming out compressed/shrinked

every time i burn an iso/image/watever larger then 700mb, something is making them burn/write like if compressed it. even though i never did.

and i just started to get this problem where all the things i burned into a cd/dvd, they looked like i compress them, even though i didnt. Like if i look at the burned cd/dvd, it looks like i shrinked the filesize, instead of looking like a 4.5gb file, looks more of a 400mb...and because of that, the things i burn usually dont come out right, some come out corrupted, quality reduces. ....

is there a setting or something that i clicked by mistake thats compressing my files every time i burn them??? how can uncompress/undo it?

im using nero, magiciso, poweriso. and im geting the same results

What burner software are you using. It appears it is using the default for a regular disc, and burning under CDRW rather than DVD parameters... I suspect it is an easy fix in your burner software, whether Nero, Creative, Record Now or other... some mistake occurred to change its configuration.
It is compressing it to make everything fit on a 700 MB disc.

What burner software are you using. It appears it is using the default for a regular disc, and burning under CDRW rather than DVD parameters... I suspect it is an easy fix in your burner software, whether Nero, Creative, Record Now or other... some mistake occurred to change its configuration.
It is compressing it to make everything fit on a 700 MB disc.

its plextor
so were do i go exactly to change these settings??

You change them in the setup for whatever burner you are using...