Finding the cause of vanishing disk space

Q: My Windows 7 laptop has been steadily losing hard disk space as new data is stored on it from a source that I can't determine. The amount of stored data has been climbing at a rate of about 270 megabytes per day for nearly five months. I haven't added anything to the PC but recommended updates and a few spreadsheets and text files. I suspect the extra data has been downloaded, but I can't find where on the PC it's being stored. What's wrong?

Chuck Goetzinger, Chanhassen

A: There are several possible causes, including Web browser files, malware, the creation of Windows "restore points" and hard-drive flaws.

Browser: Your Web browser accumulates data all the time and stores it on the hard disk. Try clearing the browser's cache, where most of the unneeded data are stored (to clear the cache on most popular browsers, see tinyurl.com/ycb7pc4s).

Malware: It's possible that malware is running on your PC and adding data to your hard drive. Run the free version of security program Malwarebytes (see tinyurl.com/jsdacdk) and the free CCleaner program that removes unnecessary hard drive files (see tinyurl.com/y826cj8x).

Restore Points: Windows regularly creates restore points, which contain the PC's settings from a particular day. (In the event of PC trouble, you can return the PC to the settings it had at the last restore point.) However, each new restore point can add hundreds of megabytes of data to your hard disk, and that may have caused the incremental data increase you have been seeing. To counteract that, you can reduce the storage space available for restore points, or you can erase most or all of the existing restore points (see tinyurl.com/z8ml2qe).

Hard-drive flaws: If the hard drive's file system software becomes corrupted, it may falsely report that some storage space on the hard drive is filled, when in fact that space is empty. That could account for your drive's apparent data increase. Try to fix the file system by running the Windows 7 "chkdsk" (check disk) software (see tinyurl.com/ze35pnr).

Jim Diffendal, Wyomissing Hills, Pa.

A: Your PC allows you to store frequently used files and programs on an SSD that has fast data retrieval time, but minimal storage. Everything else goes on the hard drive.

Eventually, the SSD runs out of space, forcing you to transfer some data or programs to the slower hard drive. Because any SSD programs will have to be reinstalled on the hard drive — and will run more slowly there — it's easier to move data. Start by copying the contents of the Documents, Music or Pictures folders to the hard drive, but leave the empty folders on the SSD to be filled with new data.

Don't tamper with the SSD's Windows files, which start the PC faster than if they were on the hard drive. The PC will look for those files on the SSD.