Mysterious Dialer Hijack

my computer is having problems with a dialer hijack. a few seconds after the first dial-up after start-up, the connection will be cut and a dialer program will immediately begin dialing an undisclosed number. this has never been successful, but it continues for some time before stopping. at this point, i get the error message:-
C:/Windows/System32/commans.com
C:/Windows/SYSTEM32/AUTOEXEC/NT The System file is not suitable for running MS-DOS and Microsoft windows appplications. Choose 'close' to terminate the application.
after roughly 15 minutes, it will go through this cycle again.

at the same time as this began, my anti-virus software told me that my computer was infected by Bloodhound.exploit6 and an associated trojan worm.

i've tried ad-aware and spybot to remove any unwanted programs. this hasn't stopped the dialer hijack attempts.

i can provide a HJT log if requested. can anyone recommend ways to deal with this problem.

 

ok, sorry for not reading through the threads before i jumped the gun and posted.

i did all the recommended steps. however, i wasn't able to access the internet with my dial-up from safe mode. i'm not experienced enough to know how to change the settings to do this. i had to do the TREND and SYMANTEC scans in normal mode (with system restore off and hidden files visible).

the TREND scan found and removed agent.ae and delf.ar- my norton anti-virus scan wasn't able to do this.

according to the SYMANTEC scan, i'm at risk to hacker exposure, trojan horses and viruses...everything else is fine. no viruses or trojans currently exists on my hard drive.

all the other scans came up with nothing significant.

the problem is still continuing.

i'm at a loss for what to do. any ideas?

 

actually, i was wrong in saying that the dialer will not connect. it will not connect only if i switch on my phone before it starts dialling. otherwise it will connect. most worryingly, i cannot get any information on what i am connected to...

it also changes my homepage from google.com to google.de when it connects.

can anyone shed some light on this?