Still not fixed - odd character in pixelpost.php
@ Dkozikowski - thanks for the tip about commenting out the @ulink line. That did resolve the problem where the pixelpost.php file was being constantly deleted.
Unfortunately, the overall problem remains: all tests pass on the configuration page, except the connection test at the end.
@ austriaka - I took your advice and downloaded Programmer's Notebook. I downloaded and opened pixelpost.php using it - made sure to set encoding to UTF-8, no BOM. When I opened the file I saw an odd character after my database password - it looked like the letters "SI" together in a block. I deleted this character so my password was correct - uploaded the file back to the includes directory - and got the same problem.
What's strange is, when I downloaded the pixelpost.php file to check it again, the "SI" character was back in my password field.
So that explains why the connection test is failing; it's the wrong password. Why is the pixelpost set up inserting this character?