It sounds like you may have a faulty rule check going on. Follow this KB to get the isinstalled rule information (what Altiris actually checks for)
https://kb.altiris.com/article.asp?article=19200&p=1
After you get what it is checking for (perhaps a version of a file or registry key), go to the machine(s) in question and check to see what is up. I'm guessing that it might be checking for a file version that is still on the machine and therefore saying it is vulnerable.
Altiris does often get the rules wrong every single month. However, they do correct it pretty fast. By now I would assume that bulletin should be accurate on the Altiris side of the house.
