By default when a partition is near being full the following message pops up:

Hard Disk is Full

You have run out of disk space on drive C. To free space on this drive by deleting old or unnecessary files, click Disk Cleanup

This can be rather annoying especially when copying files between almost full partitions. To disable this popup warning for a drive:

1. Open My Computer
2. Right click the wanted drive and choose Properties
3. On the General fan, press the Disk Cleanup... button
4. Select the Settings fan
5. Uncheck If this drive runs low on disk space, automatically run Disk Cleanup
6. Press Ok
7. A popup comes up about deleting temporary files, press Ok

The above actions are reflected in this DWORD registry value:

[HKEY_LOCAL_MACHINE \System \CurrentControlSet \Control \FileSystem]
DisableLowDiskSpaceBroadcast = 12 (Disable checking on C: and D:)

Bit	Value(Dec)	Value(Hex)	Letter
1	1	0x00000001	A:
2	2	0x00000002	B:
3	4	0x00000004	C:
4	8	0x00000008	D:
5	16	0x00000010	E:
etc.	etc.	etc.	etc.

More Info MS KB188074

Related Configure different cleanup profiles for different drives

Credits www.mdgx.com