I believe the file name is FPUPDATEAX.EXE-1BCF6D6E.pf
If this file name is correct it could be a pre-fetch file to speed loading of programs and if deleted will be replaced by the pre-fetch function later, assuming it was in the C:\WINDOWS\Prefetch folder, check the avast Log Viewer, warning section for more details on the detection. If it wasn't in the pre-fetch folder this would make that .pf file more suspicious (to me). Please let us know what information is contained in the Log Viewer about this detection (virus name, original location, etc.) ?
The first part of the file name, FPUPDATEAX.EXE does appear to be related to Macromedia Flash, a google search only brings up a 5 hits for this all need translating, but this would appear to be the location:
c:\Documents and Settings\YourUserName\Application Data\Macromedia\Flash Player\www.macromedia.com\bin\fpupdateax\fpupdateax.exe
Now this file may then have a file in the c:\windows\prefetch folder to speed its loading and that would probably be FPUPDATEAX.EXE-1BCF6D6E.pf.
Why the prefetch file should be detected is strange as I don't believe it contains the original file, just hard disk locations to make it load faster. If it did contain the original file then in theory the original file should also have been detected as infected, very strange.