PHP Errors

I run my site ( on my own, custom made PHP CMS, and it has been working perfectly for the past few months without a single hiccup. However recently, following all the downtime etc etc, it is throwing errors at me left right and centre. The weird thing is though some of these erorrs don’t seem to exist. For example, on my homepage it would return a warning saying cannot find function get_header() yet I know it is getting the header because the actual page loads correctly! It is really infuriating, at the moment I have just supressed the error messages, but I need a solution. I have contacted DH and they say they haven’t changed anything, and that they cannot help me further because it is a third party script. I know it isn’t anything I’ve done because I haven’t actually changed any code on my site in the past few weeks.

If anyone has any similar problems or has any possible solutions, please, help me.

HybridLogic : DIGi27