Reliable imac suddenly freezing/crashing

Hello. I've a normally very reliable imac 1.6GHz powerPC G5 512RAM

Just in the last few days I've been having a lot of freezes. It has almost never crashed in the 4 or 5 years I've had the imac apart from when I had a sudden hard disk failure about 2 years ago. The problem is beyond just freezes. I've been having problems after trying restarts. The imac hasn't always managed to start up and it's taken several attempts before the imac has been running again.

One thing I've been doing differently is I started using some external speakers which previously I'd used on a pc. I know it says on the instructions that I should do a restart after plugging the speakers into the computer. Is this necessary? I haven't been bothering. Another thing is I use a Griffin imic to record my voice on the imac. It's occurred to me that the imac was set up in the Sound settings to use the Griffin device that perhaps this meant the imac wasn't set up right for the speakers although the speakers have been working ok without my going into Sound settings and changing anything.

Another thing is Skype (which appears automatically on start up/restarts) is now saying "skype error valid port numbers are 1024 65535" every time I have to do a restart.

I have a piece of software called SMART utility which says the hard disk is fine.

Thanks for any help.

Third party drivers cause freezes, Uninstall anything new youve add. ..see what happens. Try to find the latest Mac drivers for your machine. After you remove the 3P drivers run disk first aid and repair permissions before you install new ones.

The only software I've installed at all lately is the SMART utility. I downloaded that because I was already getting freezes so it can't be that. My Griffin imic/Final Vinyl is refusing to allow me to record now. "An exception occurred while recording." "Recording has been stopped."

Is it possible the problems involve the external speakers borrowed from my pc that I hadn't used on my imac before?

I tried the disk repair but I've had another freeze since then.

SMART utility isn't the problem, it's very Mac-friendly - and useful.

Plugging speakers, be they pre-amp or externally amplified, directly into the iMac audio out port shouldn't cause any bother either. Are the PC speakers interlinked, ie. one has an amp in it, the other is a slave? Have you any other speakers to try?

Something else catches my attention - the amount of RAM. 512 is only just enough. Insufficient RAM can cause freezing. I would recommend 1 Gb minimum for doing sound recording.

We need also to consider a logic board fault, a cause of freezing, and not uncommon in the G5 iMac. As the l-b controls everything that goes on in the hardware dept, that should be checked and analysed. It's a job for a Mac technician.

On my external speakers the power goes into one speaker and the 2nd one is attached to the first.

Something I should have added is just before my imac freezes I'm often getting weird distorted shaping of program windows. A bit like a Salvador Dali painting.

As hughvane suggests minimum of 1GB memory.

Also try setting up a new user account and see if the problem persists.