What version are you installing? I would check their site and get the most recent version. And I would get bearshare lite here is the site
http://www.bearshare.com/lite and here is a comparison
http://www.bearshare.com/lite/downloads.htm. Lite version does not have the bundled software. I would do what I call a complete uninstall of bearshare. What I mean by that is backing up your download folder and your temp folder. Usually the temp folder is in C:\Program Files\BearShare\. If I remember correctly when you first install bearshare and run it it ask you what folder to save your downloads. As long as its not in C:\Program Files\BearShare\ the download folder should be safe. Need to backup your temp files though. Then go to add/remove programs and uninstall it. Then reboot and delete the program directory for it. Usually its C:\Program Files\BearShare. I would empty your temp files and recycle bin. Ccleaner is a good program for that. Then I would run a registry checker like regseeker. I would then restart and get the lite version and install it and put back the backuped temp and download folders for bearshare. I would run
http://housecall.trendmicro.com/ and run sfc to. Cause this is strange imo. As far as a different program I recommend emule or shareaza. Check this site out for more p2p apps
http://www.zeropaid.com/.