I've noticed an oddity in my Win XP which is now reporting the file size on disk as being significantly less than the file size. (See the images which are typical.) I've an up-to-date version of Norton AntiVirus, SpyBot, and BT Yahoo! AntiSpy, none of which reports any problems. I've also run Check Disk with no reported errors.There are no other problems and the files can be run OK. I've searched for this the Microsoft website without any success.Any ideas anyone?http://forums.avsim.net/user_files/109375.jpghttp://forums.avsim.net/user_files/109376.jpg

Any chance the files are on a compressed partition? Or that GMAX is compressing the files?DougEdited 'cause I can't spel

Just click the advanced button and see if compression is checked. It's a handy feature, NTFS compression. I use it for my Aircraft folder. This reduces the size from 5.13GB to 2.08GB currently. Aircraft compress well because they contain a lot of "raw" data like bitmaps and .wav audio files. No noticable impact on aircraft loading speed, either.

Thanks both of you, some files are compressed!It's still strange though since I've never actually set XP to compress files.

I've investigated further and found that WinXP seems to compress files automatically.I right clicked on the hard drive in Explorer, selected Properties then Disk Cleanup. After it had produced the list of space that can be savedc, I scrolled down to Compress Old Files and clicked on that then on Options. This enables me to select the time after which an unaccessed fle is compressed. The allowable time ranges from 1 to 500 days. There doesn't seem an option to disable compressing.No doubt the WinXP experts know this. I didn't and haven't found it documented anywhere. There's information about compressing individual files and folders but not this.

I've now realised you can disable compressing - just don't select Compress Old Files when cleaning the disk. However, when I cleaned up a selected everything (as one does!!) so got compression.