There have been nearly 1500 views on this topic in its first month. So contrarians take note, there is still interest in Win98!
It is arguably NOT folly to run Win98 with an outdated Avast4.8 virus database. Newer viruses are targeting current operating systems: The files they infect likely don't even exist in Win98. Members on the Microsoft MSFN forum in 2013 made a fairly strong case to run Win98 bare-ass (
no anti-virus program).
http://www.msfn.org/board/topic/162097-does-win9x-need-antivirus-anymore/. I know, you're not 100% convinced, but sometimes you can't have it all.
Scenario: Your Avast4.8 update with Win98 failed so you came here. Then you found the 9/11/15 vpsupd4 didn't work. You can't go back in time, the failed current update left virus database remnants. You're stymied. But you still want real-time protection;
some is better than
none. Here's how (not the way I did it, but rather the no-brainer method):
Before starting, read all the steps, download all the needed files. Set your Swapfile to be managed by the OS: It may expand up to 1.5Gb if you have <256Mb of RAM. Be aware that the Swapfile is slowing down the system: To speed things up, get a used/refurb 7200RPM 8Mb IDE hard drive, and/or put the Swapfile on a separate hard drive from the OS.
(1) Copy your license key. Uninstall Avast4.8
(2) Re-install Avast4.8.1368. If it fails, run AvastClear, re-install 4.8. You now have a 2009 virus database.
(3) The 4.8 re-install wants you to reboot, but instead shutdown. Disable your internet hardware connection.
(4) Boot-up. After everything initializes go to 4.8 program settings->updates (basic). Set virus and program updates to manual. Configure your 4.8 preferences. Re-enter your license key.
(5) Install the 9/11/15 vpsupd4. If you have a slow machine, consider installing a 2014 or earlier vpsupd4 from that 9/11/15 link instead (things will run faster if the database is smaller, the Swapfile won't expand as much).
(6) Shutdown. Enable your internet connection.
(7) Boot-up. You will be running the 9/11/15 (or earlier) virus database forever, but it probably won't matter. 4.8 only checks your license key when you update, so your license key will never expire.
If you’re still paranoid, go back to my previous post on using ClamWin Portable as an adjunct.
Unless/until someone finds a "magic" fix for 4.8, this is the best you can do in Win98.