Hi,
reboot the PC in safeMode, login as Admin, make sure that avast resident shield is not running (pause it if necessary).
THen navigate with file explorer to the TEMP-folder in your first posting, and delete ALL files in it
do a thorough scan (including archives) of the whole system while still in safemode
if the trojan is gone, reboot normally
if not: please post the full/complete/exact path to the file that avast finds the trojan in
- apply all Windows updates
- check/close/secure your network shares
- Install, update, scan and fix with:
spybot, ad-aware, cwshredder (DL-Links here via the board search)
- secure IE-Browser: /disable/restrict ActiveX & scripting
-exercise caution when surfing in the future