HD too fast leaves free space?

[qanda]This thread is about the Dell hard drive - 80 GB - SATA-300. Click here to see full specs[/qanda]Hello, everybody!
Computer Dimention 3000 Dell.
Primary Master- Maxtor 6Y080L0, capacity- 74.293 GB, NTFS
Primary Slave - WDC WD400BB-32CLB0 capacity- 37 GB, FAT32

Few days ago Master hard drive in my computer becomes to leave free space too fast. For example, only during one day free space goes down from 12GB to 1.6GB without any installing activities. I see this info in Microsoft Explorer, Total Commander and check with Disk Defragmenter, but
after Analyzing, Report shows, that free space is 52 GB.
The same info I got from iDisk. This program show, that only 22.37 GB used. Slave drive is working good.
If I delete same files, free space is decreasing.
I can not understand what’s happen and which info is correct.
What do I have to do?
I’ll appreciate any help.

Hi, everybody!
I found reason why my HD leave free space too fast.
I do not need help for this problem now.
Best regards,