FW: php question

>hi, sorry to trouble you, but i am a beginner php programmer and i have a quick question. i got your email from a php newsgroup. > >i'm using a statement like: > >if ( preg_match("/\\$word/i",$keywordHash[$keyID][0] > 0) >{ >... >} > >which works fine if word is a word like "reference" or even "p4dp8", but when the word is "4xAGP" i get this message: > >"Warning: back reference: to non-existant pattern at offset 6" > >or $word="4x": >"Warning: back reference: to non-existant pattern at offset 3" > > >do you have any idea what would cause this? >any help you can provide would be very appreciated. > >thanks, >Andrew >