EMac crashing more & more often (possible RAM problem?). Help, please!

Question

My eMac is a year and a half old, and the screen began to suddenly freeze up about a week ago. I first noticed the problem when playing back DVDs. After a minute or so, the screen would intermittently display a bunch of short, thin horizontal white lines along with the image, and then suddenly lock up; for a few seconds, I could still move the cursor, then that would freeze, too; the only thing that worked was to turn the power off and on again. The problem has been getting steadily worse since then. The freezing up seems to be triggered by anything that involves a lot of motion on the screen (moving a Quicktime, Windows Media Player, or VLC window around while a video is playing; using screensavers that involve a lot of motion, etc.). The white lines, however, only appear with the DVD player. Most recently,and more alarmingly, moving any window at all around, even a little bit, seems to trigger the problem, as do drop-down menus, adding bookmarks, etc.
Also, I've noticed that the problem is sometimes accompanied by a very "smeared" looking Dock, and if audio is playing at the time of the freeze it will often stutter.
After reading posts, both on this site and elsewhere, about similar problems, I've tried the hardware test on the disc that came with the computer. (Everything passed.) I've also reinstalled the OS, disconnected non-essential peripherals, repaired permissions, used the disc repair utliity (no repairs were needed), trashed a number of permssions as per advice on some websites -- all with no success. I've also spent the past week looking through the various logs and reports on the Console, but since my technical knowledge is extremely limited, this information has not been able to help me so far. Finally, there are several user accounts in my family, and this problem does not seem to be confined to any one of them.
Today, I ran memtest (www.memtestosx.org) to test my memory, and one of the 3 test sequences gave me the following error message:
"Bit Flip: testing 1FAILURE: 0xfffffefe 1= 0xfffffffe at Offset 0x03261c93"
Could this be the problem? If so, what does it mean and how can it be corrected? (All of the other memory tests were o.k.)
I'm growing increasingly frustrated and worried as this problem worsens, and I'd be grateful for any advice.

Answer 1

[snip]
Today, I ran memtest (www.memtestosx.org) to test my
memory, and one of the 3 test sequences gave me the
following error message:
"Bit Flip: testing 1FAILURE: 0xfffffefe 1=
0xfffffffe at Offset 0x03261c93"
I'd take one of the DIMMs out of the eMac and test again. If you get the error, the DIMM in the eMac is bad. Replace it. If you don't, that DIMM is probably still good. In either case, take it out and test with the other DIMM. If you get the error, then the other DIMM is probably bad. If both DIMMs show the error, you may have had two bad DIMMs (unlikely, but possible) or the test may be in error. At that point you might want to run Apple's hardware tester, which ships with each Mac. (With older machines, it was a separate CD. With newer machines, it's on the DVD.) If Apple's tester says you have bad RAM, you have bad RAM. Replace it. If Apple's tester says that you have good RAM, but the problems continue, I'd take it in for repair... or just buy new RAM and have done. Most eMac 1.25s andn all 1.42s can handle up to 1GB (Apple's official stance) in two 512MB sticks, or 2GB (reality) in two 1GB sticks.