I am not familiar with the executable z6nkxhd2uzthd.exe, nor have I seen any variants of (d2uzthd.exe, uzthd.exe, etc) - three possibilities in my eyes: a required app or it's temp file or a malicious app (intrusion of any sort).
- Have you installed any new hardware or software? If yes, uninstall and search for the app.
- Do you know how to access your start-up list of programs? (msconfig)
If yes, do so and either start in interactive mode or simply uncheck all the items on the list and continue to boot. Next perform whatever you have planned.
Adaware is an okay product, but I find
Spybot (with most options running, such as TeaTimer.) - you can
download it here.
I recommend you install the above; update it; configure the settings; use the tools and run a scan. (After the initial install and reboot it will most likely run a scan before your system runs the start-up group.
goin somewhat

Why 'get with the times' if the new era is worse than the old?
I do not blame you one bit -- I have built most if not all the desktop PCs as well some servers for our company and of all the Microsoft operating systems, 98 SE has given the least amount to problems (not including 3.1 and older). It is on a well used client support box and has been for over five-years.
How I see it; if you are going to say 98 is shit, why stop there ... all MS is shit - go BSD or Linux (such as Lindows).