I'm currently deliberately infecting a spare machine just so I can play around using the various removal tools. Its very addictive and fun too. Why?? Why not..
MSNB.downloadhost is something to do with MSN DownloadManager. I assume you have this installed, if so try reinstalling it, or get rid of it. Some more info would be useful too What Operating System are you using? What Browser and version are you using? When did this problem start? Have you had issues with it before? Have you recently installed this or other software?
I would also suggest you scan for viruses as there is a worm called msbn
Did the previous reg file work? What happened? OK, I couldnt find the file to enable the SC AV and Firewall monitoring feature on the net again but here it is in text form. Copy everything between the === lines into notepad and Save as SCenablenotify.reg (the name isnt important, makes it easy for archival perposes, just the extension) Please ensure you have the extension changed to .reg or it wont work. Once youve created the .reg file, right click on it and Merge.
I came accros this issue on a friends PC a while ago. I solved it with a couple of .reg files, cant remember where I got them from but Ive still got them myself.
Just had a very quick, cursory glance at your log and noticed that your Java Runtime is out of date. You are still using j2re1.4.2_05 Uninstall it and install the latest version. Version 5.0 Update 6