Very low on detail, no analysis what caused this. I've never had issues with ram upgrades. Ram either works fine, or it reports errors in memtest (or reports errors under high load).
Chance of ram issues causing other hardware failure... ZERO
Chance of ram issues causing other hardware failure... ZERO
Except that when I procured an external modem it reproduced the exact same issue.
A lot of time was wasted trying to figure out what happened. Several fruitless rounds of OS reinstalls later I started to swap test any removable component out of desperation (there really wasn't many on a laptop) and voila the problem went away once a particular stick of RAM had been removed. Later tests found that it will pass most tests in MemTest86+ except this a copy operation over repeated runs.
I have no idea why the symptoms were so peculiar, perhaps when using dial-up connections the OS had been repeatedly loading the network stack in the memory address close to the affected blocks and after a while it will inevitably encounter a IO error and crash. This is just one personal anecdote, but with a complex system it is certainly possible for RAM issues to appear like other kinds of failure.
Odds probably the RAM was mismatched, and the BIOS did not choose conservative settings. Also could be voltage mismatch, and then your low voltage modules could fry (unlikely though).