Sudden decreasing disk space (is this a virus?)

I have just freed some space from my macbook. I freed about 5 gb of data. SO I was aware the whole time that the space I had in my macbook is still about 5 gb after I transferred those data. After a few hours I got a message saying "the startup disk is getting full.."

I checked the free space and it was now 335 mb. I was listening to 181 FM the whole time it happened. I closed 181 FM.. now it became 500 something mb. Then restarted my macbook, now it's 937 mb. I'm not sure if it's related but I don't think streaming can eat up that big amount of space.

I didn't know how it happened. I didn't do anything, didn't download or transferred any files (as I've said, I freed some 5gb of data hours before). Emptied trash.. etc.. but still the same.. I'm wondering where did those 4+gb data come from?

I hope you can help me out here. I'm so clueless. Didn't know where to find and erase those data.

Can't say, but I can assure you that it is not a virus.

How much total capacity does your hard drive have? I've learned a rule of thumb that says you should keep about 15% of the drive free. In fact, I learned it the hard way when a disk starting having less than that and started acting strangely. Since then I make sure to keep a good 15% free and do regular maintenance.

Hello!

Thank you very much for your replies. I guess I'm learning it the hard way too... I never did any maintenance to my Mac for a year++

except for those automatic updates and battery calibration...

The links you provided are great! I will surely try it. And as of now, I cleaned my hard drive and left a good 15% and more space. I just panicked when this weird decreasing space suddenly happened. I thought Macs are impregnable from viruses. Turns out, it still is. So glad

The 3rd-party utilities "OmniDiskSweeper" or "Disk Inventory X" or "GrandPerspective" or "JDiskReport" will help show you where the disk space is going.

Alternatively, open a Terminal window (Terminal is under /Applications/Utilities) and enter the following command:
sudo du -x -h -d 1 /
Look to see which sub-folder is taking up the most space and repeat with that folder. If you have trouble interpreting the results, just copy & paste them back here and we can help.

~ MAC OS X - Losing Hard Disk space daily

Are you not try protect your mac with ProteMac NetMine? I use this prog

dasli dasli wrote:Are you not try protect your mac with ProteMac NetMine?

Protemac Netmine is a firewall. Being a good (and, frankly speaking, in many cases really sufficient) tool for protecting OS X, I guess, it's not exactly what the thread-starter needs to remove a virus.

Again, it is not a virus. There are no viruses for OS X in the wild. A Trojan that the OP installed? Perhaps. But not a virus.

More likely, some program just wrote some big files. A program such as Omni Disk Sweeper can help find large unused files.