Intel MacBook + 10.4.9 = application crashes :-(

Question

After updating our MacBook (Intel) to 10.4.9 using the software update several applications crash on startup and others under other conditions. Some examples ...
(1) iChat crashes after about 15 secs, but after connecting to the AOL server.
(2) iTunes crashes immediately.
(3) Skype crashes just after we become "available".
(4) Safari crashes when we click on the "Mac OS X" tab of the apple site.
(5) Editing of pictures in the address book or in the "Users" pane of the "System Preferences" also results in a crash.
Another user posted he had problems with the KeyChainAccess, but that the application ran fine under Rosetta ... I tried iChat under Rosetta and found that it worked fine also. The post referring to the KeyChainAccess problem is here
http://discussions.apple.com/thread.jspa?messageID=4225941&#4225941
It is possible that our problems are related to the KeyChainAccess. Although running KeyChain First Aid did not improve upon the situation.
A second KeyChain experiment we ran was to create a new account and try running iChat from there. In this instance, iChat crashed immediately.
Another feature of the update is the presence of an occasional faint repetitive clicking sound (the hard disk I think) comes and goes. When audible, we get the spinning beach ball and the system is non-responsive.
Beyond that, my internet connection appears very slow. However, there is presently no conclusive indication that apparent slow connection speed is related to the update.
Next on the plan, is the Combo Update. Due to our unusually slow internet connection, I'll have to come back and report on the result in an hour or so.
PBG4, iMac (G4 flower pot), iMac (Intel), DualG5, MacBook   Mac OS X (10.4.9)  

Answer 1

I've applied the Combo Update for 10.4.9 over the Intel Update applied by Software Update.
Nothing changed. The same applications crash.
Here are snippets from the crash logs
iChat.crash.log
Thread 0 Crashed:
0 <<00000000>> 0xffff0633 __bzero + 51 (cpu_capabilities.h:226)
1 ...ickTimeComponents.component 0x9c819091 run_decoder + 947
2 ...ickTimeComponents.component 0x9c81bf61 encoder + 5724
iTunes.crash.log
Thread 0 Crashed:
0 ...ickTimeComponents.component 0x983bdaa3 ChannelComponentDispatch + 0
1 ...ple.CoreServices.CarbonCore 0x903f5a22 CallComponentOpen + 43
2 ...ple.CoreServices.CarbonCore 0x903f4f26 OpenAComponent + 436
Safari.crash.log
Thread 0 Crashed:
0 ...ickTimeComponents.component 0x984e9a7b NullComponentDispatch + 47
1 ...ple.CoreServices.CarbonCore 0x903f5a22 CallComponentOpen + 43
2 ...ple.CoreServices.CarbonCore 0x903f4f26 OpenAComponent + 436
3 ...ple.CoreServices.CarbonCore 0x903f4d09 OpenADefaultComponent + 115
Skype.crash.log
Thread 0:
0 libSystem.B.dylib 0x900247e7 semaphorewait_signaltrap + 7
1 com.skype.skype 0x0045c7ef 0x1000 + 4569071
2 com.skype.skype 0x0045ceb1 0x1000 + 4570801
3 com.skype.skype 0x0043ed54 0x1000 + 4447572
Since it appears that QuickTime may be implicated, I decided to reinstall QuickTime 7.1.5
... and ... <drum roll> ... That did the trick!
Hope my frustration helps someone!