You need to think with Portals!
Look up in the direction you are heading to the fire; you can spawn a portal on the wall up there, one to your right, and teleport out of danger.
After that, keep trying to reach the party to get your promised cake!
According to the ASCII art it's "GLADOS"
Check this page. Look at the second post, click Show and scroll down to GLADOS you'll see the same ASCII art there in reference to that name.
EDIT: In case that page goes away here it is
"GLADOS1" "[12.000] #+ @ # # M#@ "
"GLADOS2" "[12.000] . .X X.%##@;# # +@#######X. @#% "
"GLADOS3" "[12.000] ,==. ,######M+ -#####%M####M- #"
"GLADOS4" "[12.000] :H##M%:=##+ .M##M,;#####/+#######% ,M#"
"GLADOS5" "[12.000] .M########= =@#@.=#####M=M#######= X#"
"GLADOS6" "[12.000] :@@MMM##M. -##M.,#######M#######. = M"
"GLADOS7" "[12.000] @##..###:. .H####. @@ X,"
"GLADOS8" "[12.000] ############: ###,/####; /##= @#. M "
"GLADOS9" "[12.000] ,M## ;##,@#M;/M#M @# X#% X# "
"GLADOS10" "[12.000].%= ######M## ##.M#: ./#M ,M #M ,#$ "
"GLADOS11" "[12.000]##/ $## #+;#: #### ;#/ M M- @# :"
"GLADOS12" "[12.000]#+ #M@MM###M-;M #:$#-##$H# .#X @ + $#. #"
"GLADOS13" "[12.000] ######/.: #%=# M#:MM./#.-# @#: H#"
"GLADOS14" "[12.000]+,.= @###: /@ %#,@ ##@X #,-#@.##% .@#"
"GLADOS15" "[12.000]#####+;/##/ @## @#,+ /#M . X, "
"GLADOS16" "[12.000] ;###M#@ M###H .#M- ,##M ;@@; ###"
"GLADOS17" "[12.000] .M#M##H ;####X ,@#######M/ -M###$ -H"
"GLADOS18" "[12.000] .M###% X####H .@@MM@; ;@#M@ "
"GLADOS19" "[12.000] H#M /@####/ ,++. / ==-, "
"GLADOS20" "[12.000] ,=/:, .+X@MMH@#H #####$="
Best Answer
Some of the files probably got messed up when you were downloading or something. Go to your steam library, right click on the demo and click "properties", then go to the "local files" tab, and then click "verify integrity of game cache" fixes a lot of issues like that for me.
This only works if you're playing via steam though.
If you dont mind losing your progress to that point, you can just uninstall and reinstall and it should work fine.