XP warns you on three different occassions with messages related to low disk space. when this is true : 80 MB < free disk space < 200 MB The following alert displays for 10 seconds, once per session: You are running out of disk space on [drive]. To free space on this drive by deleting old or unnecessary files, click here. when this is true : 50 MB < free disk space < 80 MB The following alert displays for 30 seconds, every four hours, twice per session: You are running very low on disk space on [drive]. To free space on this drive by deleting old or unnecessary files, click here. when this is true : 0 MB < free disk space < 50 MB The following message for 30 seconds, every five minutes, until free space is above 50 MB: You are running very low on disk space on [drive]. To free space on this drive by deleting old or unnecessary files, click here. Navigate to [HKEY_CURRENT_USER\Software\Microsoft\Windows\ CurrentVersion\Policies\Explorer] and look for the data key "NoLowDiskSpaceChecks" and set its value to 1 to disable low disk space check