Precision M4400 BIOS Question

I have an offlease-refurb'ed Precision M4400 laptop which frequently, when booting the system, shows the BIOS (version A29) progressbar at normal speed up to about 80%, at which time it slows down such that to complete the initialization and handoff to boot takes close to 5 minutes. Once this completes the system boots fine into either Windows or Linux. Other than this issue the system has no other issues.. 

What is this slowness telling me??

Thanks

Dave Frandin