Queries don'twork any more - urgent!

Hi,

I'm using 8.1.5 on Red Hat 6.1.

Certain (similar) queries have stopped returning any results. They were working fine, and then suddenly stopped. I'm 99% certain I have done nothing which may have caused this.

Where the hell do I start to find out what's wrong? I'm at home and so don't have Oracle Support's 24/7 support phone number (England) with me. If anyone could remind me of it (mail me direct) I can ring them.

thanks,

• Kev