A few weeks ago I installed a Crystal 2.0 Pro into a v4 PAL PS2. The chip worked fine and booted both ps2 and ps1 backups with no problems.

Then, yesterday, I suddenly started to notice some disc drive performance degradation. At first it occasionally refused to read discs while I was playing a backup and the game showed a disc read error message (an in-game message, NOT the red DRE screen). However, if I waited for a few seconds it continued to read the disc again just fine for ~20 seconds then the same thing would repeat all over. I noticed that the errors became more frequent as time passed.

When I turned on the PS2 today, the disc drive wouldn't open any more when pressing the eject button, sometimes the screen went black after pressing eject, sometimes it just ignored the button press, even the blue led didn't blink. Also after a few resets it sometimes didn't boot at all and blinked the green LED, then (without me touching any button) sometimes increased the cooling fan's RPM and sometimes stopped the fan. Afterwards it booted up fine again, however not once did I get the disc drive to open. So I removed the case and put in an original PS2 disc, it didn't recognize it. The disc didn't even spin up.

So I thought the laser might be fried and replaced it with another KHS-400B I have laying around but nothing changed. The replacement lens worked fine the last time I tried it in a v3 PS2 so I'm pretty confident that the lens isnt the problem.

I also removed the modchip and made sure there weren't any shorts - found none. Also, nothing changed after the modchip was out.

All the firmware versions in the versions screen of the BIOS seem correct and none is blank. Most of the time the PS2 boots up fine, the control pad works and I can, for example, read and erase memory card contents, set the clock etc. Problems occur mostly right after I press reset or eject.

Has anyone got an idea what could be wrong here?