isapnp refers to ISA Plug and Play. The error is produced when a hardware device is not compatible with ISA Plug and Play so Windows is looking for the file. Essentially it is a vendor driver problem.This Microsoft Knowledge base article discusses the issue with a particular sound card:
KBA 299902
A way to find the offending hardware is listed that may point to the particular hardware on your machine. They recommend contacting the maker of the device or the maker of your computer if it is an OEM system. Since you mention that you do not have the Windows CD, probably it is an OEM system. The file may be found on the recovery disk (if you have one) or the recovery partition (if there is one). With the attempted installation of the chipset drivers the plug and play feature of the particular device (what ever it is) does not work and you get the error.
You may also type "isapnp" into the Microsoft Knowledge Base Window for additional info about locating the non-compliant device and fixing the problem. Unfortunately most solutions require running the Windows recovery console and without the Windows CD you will not be able to do that.
Welcome to the Via Forum.
Jim