Question : Problem: TiPowerBook makes beeping noise; is this a warning?

Help again!  This question relates to my question on Jan. 14th regarding the ventilation fan on a TiPowerBook G4 500mhz.  Peripherals are printer and Zip drive (USB), no Firewire used.  I thought this problem had been solved, until yesterday.  

All of the sudden, my TiPowerBook gave off a 'beep' noise.  (Sounded a bit like when someone is leaning on the keyboard on a PC, but softer).  About 10 minutes later it let out a series of beeps (3).  So quiet it took me a minute to realize it was the Mac.  A few minutes later the ventilation fan kicked on (it's been quiet lately).

At the time of the beeping I had MS Word, MS Excel and Netscape open (online).  I quickly shutdown the MS programs and the fan turned off after a minute or so.

Is this beep noise some sort of warning related to overheating?  I've never heard this before (and have been using Macs and PCs for 15 years)!  I searched Google but didn't see any mention of this anywhere.

Thank you AGAIN for your help.

Answer : Problem: TiPowerBook makes beeping noise; is this a warning?

I have configured a number of t-books for clients and have never ran across a "beeping sound."  

As to the fan, MS is a real pig and uses alot of sys. resources. That's the fan issue and it's normal .

If the CPU was going to overheat, it would shut down.