China DOS Union

On my machine, RUNDLL32.EXE shows up both in the startup items and in the processes. Is this file a required system file? It always wants to access an external connection. When I deleted it, I couldn't open some files anymore, so I had to restore it from the Win98 CD. But then it wanted to access an external connection again. I'm afraid it might be a Trojan. I used Tianwang and Norton, and both said there was no virus. Yesterday I wanted to restore with GHOST, but under DOS it actually couldn't restore. The registry couldn't be restored either. I reformatted drive C:, then the CD couldn't auto-run, so I couldn't install it. Later GHOST was able to restore again.
Question for the moderator!!!

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KO says: next time please don't post this kind of title that doesn't express the content of the post

Use the latest Rising antivirus and scan it. It's very likely some kind of Trojan.
Also, you don't even understand your own problem clearly, so it's useless to come here asking for help. First you need to figure out where the problem is. Why couldn't Ghost restore at first? Why could it later? What changed that made it work again? Why couldn't the CD boot? Was the disc itself unbootable, or did you simply not set it to boot from CD?
If there's a problem, first try working on it yourself. Don't come here shouting for help when you can't even describe the fault clearly. That way nobody can help you.

I suggest you go to the Windows directory and check whether there is a run32.exe or similar file. If there is, then maybe it really is a Trojan. Please use the file from the installation CD to replace it, and be sure to do the replacement under DOS. Also, rundll32 is a required system file. Many programs need it in order to run. Its function is to run DLL files as programs.