10.4.6 is killing my Mac Mini

Question

Please help. I am new to Mac.
I have a Mac Mini G4. I installed through Software Update 10.4.6. Partway through through the installation process, the system said there was an error, that the package was moved to the trash and that I should try re-installing. So, I did. And the same thing happened again. I tried re-booting the computer. In "About This Mac" it says that I have 10.4.6. But now, everything is messed up. I can't mount any disk images on the desktop (I checked, and .dmg files are associated with the right application). I can't even install any software. Someone had posted an ftp that had 10.4.6 as a .sit file rather than a .dmg. However, when I downloaded it and tried to run the installation package, partway through, it stopped saying, "There were errors during installation. Please try installing again later." I tried to "Archive and Install" from the Tiger DVD (10.4.0), and, early on in the installation, it gave me the same "error" message. I tried to repair disk permission (I hadn't done than before downloading the update), but it just hangs there (how long is it supposed to take anyway). Moreover, Mail won't launch and while Safari launches, it crashes. Firefox works. Please, please help me. I don't understand what's going on.
Mac Mini G4   Mac OS X (10.4.6)  

Answer 1

Thank God, everything is OK, again.
I posted my question on two forums, “Using Mac OS X Tiger” and “Installation & Setup” because I wasn’t sure which one to go to, and received useful information from everyone involved.
I want to profusely thank everyone who helped, not least Dr. Smoke and his extremely useful Web site: www.thexlab.com
Here’s what I did:
First, I tried to Repair Disk from the Tiger install DVD. The repair failed, gave me the following error:
“Invalid volume free block count
should be 15966423 instead of 15966422
Error: underlying task reported failure on exist
1HFS Volume checked
1 volume could not be repaired because of an error
Repair attempted on Volume 1
Could not be repaired”
In looking through Dr. Smoke’s site, I saw that it said that third party applications like Disk Warrior might be able to help. It reminded me that my friend made me get that program when he sold me his Mini (sorry I didn’t mention it earlier). I booted from the Disk Warrior CD and told it to repair the disk. And guess what: it actually worked!
While I still had the same problems: could not mount disk images, etc. I was at least able to do an Archive Install of 10.4 (I followed all the specific instructions as outlined). And that worked, too. Now, everything is working again!
I updated to 10.4.5 (I figured that was the last one working OK, so go with what works. I am sure 10.4.6 is fine, but as the xlab Web site notes, “Before installing software updates, you should decide if "now" is the right time.” And, frankly, after what I have been through, “now” is certainly not the right time.
One last question: all the applications seem to be working just fine. How do I delete the “Previous Systems” folder? Where is it located? Is the procedure the same as the one outlined in this document, “Mac OS X 10.2: How to Delete a Previous Systems Folder” (http://docs.info.apple.com/article.html?artnum=25461) or is it different for 10.4?
Again, thank you so very, very much for your help. I really appreciated it.
Best,
Amir
Mac Mini G4 Mac OS X (10.4.6)
Mac Mini G4 Mac OS X (10.4.6)