You have more than 100GB of hard drive space when you check your total folder size, it near to 50 GB, but you have only few GB left on your hard drive. Do you have this problem in your Windows XP computer? The reason is that your hard drive is taking more space for some other hidden files and activities log file. Let us go for the solution to clean up.
1, Clean up your disk using the disk cleanup utility. Select all to clean.
2, Make sure that you considered the hidden files and folders when you try to find out the total size.
3, Check the drive with anti-virus. Still, you have the space difference, try the following.
For temporary purpose do the following and find out and change in free space.
1, restoreTurn of your hibernate option in system power properties. (It take almost the size of your RAM)
2, Reduced the allocated size of restores to minimum in system properties.
3, If your drive is partitioned, change the page file size (virtual memory) to a different drive and after all restart the system and
check the file size.
If you see the change, do not forget to make all these changes to previous condition for your system stability.
Note: If the space missing in a different drive, run Drive:recycler. Its an recycle bin for each drive. Clean it.