Can't do last two steps

I am using Windows XP. AFAIK completely updated.

I started with the "readme" section, as directed, and went on to the malware removal processes, but I get stuck with ComboFix and MGtools. Both Combofix (which I am launching from the Desktop) and MGtools (which I am launching from C:\MGtools) give me the same error:

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Windows cannot access the specified device, path, or file. You may not have the appropriate permissions to access the item.
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OK
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I have tried re-downloading said files as well as renaming them. No dice. I am on an administrator-level account as this is my home gaming rig. I've attached the logs from the processes that did work. Any help would be greatly appreciated.

There are three undoubtedly-bad files on the root of my C:\ drive (that are visible, at least) that I haven't deleted yet as I was unclear if deleting them would be the proper procedure. I've listed them here as a search in the log files attached didn't yield any results.

brnqslpc.exe
khryeey.exe
uybkajit.exe