Are you doing Noise Removal first? When you record a song, then do nothing else except Noise Removal, the problem happens?
Which effects, in which order?
Do you have Norton? In Audacity, please look at Edit > Preferences… then the Directories section. Where is the temp folder located? If you create a new folder in Explorer that does not have “temp” in its name, copy the folder address from the address bar in Explorer, then paste that address into the “Location” box, OK and restart Audacity, does the problem go away?
Are you Dalen? If not you will need to be logged in as an Administrator to write to other users’ space.
Do you have Norton? Or other apps that clean your temporary disk space for you?
The “Location” box is in the Directories section of Audacity Preferences. Those instructions ensure you will have a temporary folder location that does not have temp in its name, in the hope of foiling any cleanup apps you have that are misbehaving.
Or you could look to see what cleanup apps you have and configure them to leave “C:UsersDalenAppDataLocalTempaudacity_temp” alone.
Or you could File > Save Project As… when you start each new piece of work and save a project. Then cleanup apps should leave your data alone.
At its simplest, you could open Noise Removal and type out the name of each setting and how the slider or radio button is set.
The value of the settings that have sliders is displayed in the text box for each setting.
Yes having no disk space would corrupt the project, but not normally in such large discrete chunks.
If you open Audacity’s Directories Preferences it always says how much space there is on the drive that holds the temp folder.
Is this a Solid State Drive with limited space? You should be aware that by default Audacity uses 20 MB of space per minute for stereo audio. If you import a 5 minute stereo song, that is 100 MB of space. If you edit that whole length of song with five effects, that is another 5 times 100 MB, for a total of 600 MB.