You're running Windows 7 and Windows XP on a single PC, but keep getting messages saying that there is no free disk space. Our Helproom Expert advises.

QUESTION I'm running Windows 7 on my C drive and used EasyBCD to dual-boot XP on my D drive. In XP, a message pops up suggesting there's a shortage of disk space on the C drive. There is plenty of space, however, and this drive is reserved for Windows 7 in any case. You advised me how to block the message in the Registry, but it still appears when I try to install software. Is this a Bios issue? Brian Yates

HELPROOM ANSWER This isn't a Bios-related issue, Brian. It's a result of the different methods XP and Windows 7 use to partition a hard drive. Having taken a closer look at your system configuration, we can see that one of your hard drives contains two partitions and the first of which is very small at 100MB.

This partition is created automatically during a standard Windows 7 installation; it stores the files necessary to boot the operating system and help recover the machine should anything go wrong.

Most users never see this hidden partition as it isn't assigned a drive letter. The second partition is used for the operating system and user files, and is assigned the default drive letter C.

In its old age, Windows XP doesn't know how to deal with this setup. Its found the hidden partition and called it drive C, while its own partition is labelled drive D.

The 100MB partition isn't designed to store user files. On your system it's completely full, suggesting that at least one of your programs has assumed that drive C is the correct default drive for storage.

Software should install itself on your default system drive (D), but the more common location for this is C. When this happens, the 100MB partition will fill up very quickly. To prevent this from happening, make sure you select the Custom option when installing software and ensure that the program is installed somewhere other than drive C.

Your XP setup appears to be configured to use the C drive, but you will also need to enter each application's settings menu to ensure none are attempting to use the C drive as temporary storage.

Use Microsoft TweakUI to hide the 100MB partition from XP. Launch TweakUI, then select My Computer, Drives and deselect any you want to hide.

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