Image upload - temp dir not found?

[eluser]#1313[/eluser]
Hi there.

I am uploading an image to my server. Everything works smoothly, until i decide to upload a big file (2+ mb). This gives me the really weird error from image_lib, something like this:

Code:

./tmp/ not found.

This obviously happened because of my max_upload_size variable, and i fix the problem by upping this limit from 2M to 4M in my php.ini. Okay, the big file uploads.

And then after a few hours i receive this error message again, this time with tiny 1.62mb image. My code is unchanged, and other smaller pictures are uploading correctly.

So, my two questions:
1. Isn't this "temp dir not found" message somewhat vague? I have a feeling that it says "Error! Go figure out what really happened by urself, lol".
2. What the heck is actually happening, lol?