So, here's my deal:

I'm clickity-clacking away at my keyboard, trying to whip up some PHP magic for my site, and I get messages along the lines of

Warning: fopen(http://deathdark.tfcph.com/members/userID.dat) [function.fopen]: failed to open stream: HTTP wrapper does not support writeable connections. in /home/deathdar/public_html/members/register.php on line 35

This is not the first time that I've gotten these messages, and they're really dragging me down. I can only open in read or append modes, and includes don't work at all, which sucks hard. I've played around with my permissions settings a little, trying to open it up, but when I try to go anything above the presets of 0644(document) and 0755(folder), I get a 500 message (Internal Server Error).

Can I get some help?

It's been a REALLY long time since I've been on here, but hey, if you're still stuck on this today might be your lucky day!

rather than trying to open the url to that file, open the path to the file (I'm guessing that'd be /home/deathdar/public_html/members/userID.dat)
that should fix your problem (basically, you can read a file over HTTP, but you can't write to it, which is causing the error).