You said that you downloaded the "fix" from Microsoft, so I assume it is most likely the one mentioned in this Microsoft article, "2351 and 2355 Internal Errors When Installing Software from CD-ROM" (Article number Q296742). See the article at this link:
http://support.microsoft.com/default.aspx?scid=kb;EN-US;q296742
(REMOVE SPACES from the pasted URL)
That suggests the file "Instmsi.exe" is available for download from the Microsoft Download Center.
If that is not the file you downloaded, see that article for the download link.
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If that is indeed the file you downloaded, you might try a different CD ROM drive. With a Windows 98 machine you most likely have an older and slower drive. Perhaps you could borrow one - one that is newer and has a much faster read speed. Or it might be time to buy a newer and faster one. (They are relatively inexpensive.) Or, if you have access to a network, try mapping a drive to a shared CD ROM drive on the network, and load the software from that.
Good luck,
Maxwell