TMP are normal behavior under normal circonstances. If it it filling you client hard drives then there is 2 possible problem.
- Confirm that your server is processing eventqueue properly, you should always have a near zero queue.
- Check if a job is spamming your client, like repeating every second.
That being said, Altiris temp file are usually 6 characters long not 4. How are you sure this is generated by Altiris ? You can edit those file with notepad to check, if the file start by MZ then this is an executable, you can rename the file to .exe and right click property on it to see details like manufacturer et product name. By example on my computer I have a bunch of adobe flash player XXXX.tmp