I don't have an exact answer for your problem, but the following are suggestions.
Do you use the modem?
Can you disable it in control panels?
Rebuilding the desktop can sometimes help weird OS 9 problems.
Zapping the PRAM can also sometimes help weird OS 9 problems.
Running the third party utilities Techtools 3.0.9 by Micromat or
Disk Warrior 3.0 by Alsoft can sometimes eliminate bizarre Mac behavior by
repairing disk and file structures.
Below are links to Mac help sites:
http://www.macfixitforums.com/ http://www.info.apple.com/ http://discussions.info.apple.com/
Good luck.