IIgs playing funny buggers

[alelee@praetor.hna.com.au (Alex Lee)]

My IIgs is starting to frighten me.  For some unexplained reason, 
seemingly random, the keyboard will chuck a major spaz.  Either it simply 
doesn't allow input from the keyboard (even including a reset!) or the GS 
receives waves upon waves of the same character.  Interestingly, when I 
disconnect the keyboard, the waves and waves of the same character 
continue, even when the keyboard is then reconnected to the ADB. Pressing 
another key seems to stop it (after disconnecting and reconnecting).  
Also, if the keyboard seems to do nothing, the mouse still works perfectly.

My GS is a ROM01, entering its 10th year with a ZipGSX running at 
8Mhz/16k cache, 40meg Vulcan, Sonic Blaster and 2 1/4 meg RAM.  Any 
ideas?  Is this a simple case of ageing and beyond repair!?  Reply 
responses (good news :-) to me via email.  Thanks in advance.

LaTeR!

Alex Lee - alelee@scorch.hna.com.au