URGENT: undefined control sequence: \maketitle

Dear all,

I have found an e-mail which has the same problem as I do when I was 
trying to printout pdf files using prosper class and latex.
I tried following the suggestion (use latex --> dvips--> ps2pdf) in the 
reply, but still have have the error.
Can anyone please help me to solve out this problem?
this is very urgent!
Thanking you in advance.

Regards
candy


Here is the last few lines in the log:

LaTeX Font Info:    Try loading font information for U+msb on input line 11.

("C:\Program Files\MiKTeX 2.5\tex\latex\amsfonts\umsb.fd"
File: umsb.fd 2002/01/19 v2.2g AMS font definitions
)
! Undefined control sequence.
<recently read> \c@lor@to@ps
                            
l.11 \end{slide}
               
?
! Emergency stop.
<recently read> \c@lor@to@ps
                            
l.11 \end{slide}



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