DWH* Trojan Bloodhound.PDF.1

I'm having some serious problems with a trojan and don't know what to do.  At random times, or at some startup times, I get popups from my symantec autoprotect telling me that there is a malicious trojan file in my temp file that is always DWH***.tmp (e.g. DWHAB5.tmp). It shows on symantec as "Bloodhound.PDF.1" Each time, the number of temp files grows, I'm up to about 16 now at each instance of generation.  For every infection, there is an infected file, and a browser cache. Also, the file name of the temp file always starts with "DWH" and then ends in another random 3 characters. Symantec's web pagee reports that the risk level is very low, however, I'd like to deal with the problem. I am also aware that the temp file is appearing as a "heuristic detection for reporting PDF files that contain javascript that may have been obfuscated or encrypted to conceal it from antivirus software." If anyone has any ideas, please let me know.