It makes my life impossible to live :‘( :’( 
If someone knows how to remove it, please help me
Can you give us a bit more info like what’s your OS (Windows 95, ME,XP Etc.)?
What’s your firewall?
Can you also give us a hijack log?
What internet Browser your using?
What version of avast! are you using? Last update?
If you like, you can use the avast! virus cleaner. You can download it here:
http://www.avast.com/eng/down_cleaner.html
or use the online scanner
Note: Did you send this virus to the Virus chest? If so, you don’t need to worry much.
i got that before but avast webshield alerted me of it and i disconnected off internet,might want to try ewido(free)scans for trojans or a2 squared(free)- run a full thorough system scan with avast.if that dont work you can try a program called spy emergency(trial-15 days)i know that finds it if its in your system,bri
Try the counseling by Bri. I f you don’t remove the malware, download and run AdAware and SpyBot Search&Destroy: I kbow this 2 tools surely find and remove this type of garbage! ;D
A search of these forums for ‘Istbar’ without the quotes will no doubt return many hits as this topic has been previously discussed a number of times.
Okay I found this info from ZoneAlarm:
Ewido for trojans.
MINIMUM SECURITY =free; =one-time fee (keep all current!): XP, ZA, Ewido*, AV (VET or EZAV or Trend or McAfee), MS AntiSpyware BETA*, Spybot*, Mozilla*+PrefBar*, Script Defender*, Spyware Guard*, MRU Blaster*, Spyware Blaster*, MailWasher Pro** (&/or Benign**). External Port Scan (no install)*: Sygate (weekly, +after installs).
Beware any non-Guru hiding actions in private email.