Lost windows explorer search, Advanced System Care disabled

I am running Windows XP, sp 3 on an ancient Dell 2300 desktop. Yesterday, the left panel on Windows explorer disappeared and I can no longer bring up the explorer search function. Also yesterday, all the files in the IObit folder were changed by the addition of '.AT' at the end of every file name effectively disabling Advance System Care. I deleted the directory and reinstalled ASC. It was through this process the I discovered the changes in Windows explorer.

This machine gets checked almost every day because it is used by 9-year-old son who often downloads things he shouldn't. I have been unable to create separate user accounts on the machine so all users have administrator privileges. I have managed to deal with problems in the past but I am now stumped.

I have attached the logs indicated on the removal guide. Any ideas?

Thanks

 

I did install Anti Toolbar base on a recommendation from Major Geeks. Although Hitman Pro identified Cobra on the system, there doesn't seem to be any trace of it. It couldn't find it to remove it and a search through the registry for the entry identified came up blank.

I ran the system file checker and it found corrupt files. I assume the ones that manage Windows Explorer are among them. Unfortunately, my version of XP was cobbled together after a serious computer mishap about a year ago. I had to replace the hard disk at the time and could not come up with original installation disk so my version of XP was cobbled together from several downloads. I will download a file manager to replace the non-functional Windows Explorer. That should hold me until I can replace the whole antiquated system.

Thanks for your help.