I updated it today using the internal updater, now whenever I start it up wmiprvse.exe starts up along side it. I’m on windows XP and the only plug in I’m using is Flash 12.0.0.44. I asked my friend who’s using Windows 7 without Avast, so I’m trying to get more data to see if it’s just me, just XP users, or just Avast users or some mix of causes.
upload suspicious files (wmiprvse.exe) to www.virustotal.com and test with 40+ malware scanners if tested before, click new scan
post link to scan result here
if you want a full malware check, follow the “logs to assist in cleaning malware” guide at top in viruses and worms forum section
attach the requested logs and a malware expert will take a look
The problem is I’m not sure exactly what wmiprvse.exe it is and this only started after the Firefox update, I assume it’s the normal wmiprvse.exe and I’ll try that now.
Edit: https://www.virustotal.com/en/file/64389fad94d54e2d43a7292ad3c57cb16f90f2c80ea44099e02d11e19e390a5b/analysis/1391670311/ Came back clean.
that file should be OK 
First submission 2009-04-15 09:12:42 UTC ( 4 years, 9 months ago )
Copyright© Microsoft Corporation. All rights reserved. Publisher Microsoft Corporation Product Microsoft® Windows® Operating System Original name Wmiprvse.exe Internal name Wmiprvse.exe File version 5.1.2600.5755 (xpsp_sp3_gdr.090206-1234) Description WMI