Just downloaded again (started 00:05) got exact same file, no problem reading.
Can read in linux with Okular 0.10.4 & GIMP 2.6.8, also in Android QuickOffice 3.3.74. Also printed at work from Acrobat (unknown version).
Can only presume you folk are getting corrupt downloads, file size should be 18,413,124 bytes
[UPDATE]
Actually there does seem to be something odd - although both my downloads have the same file size they are NOT identical!
chris@server:~/Documents/Le Mans>
chris@server:~/Documents/Le Mans> ls -l caguide2011*
-rw-r--r-- 1 chris users 18413124 2011-06-03 00:07 caguide2011a.pdf
-rw-r--r-- 1 chris users 18413124 2011-06-01 00:02 caguide2011.pdf
chris@server:~/Documents/Le Mans>
chris@server:~/Documents/Le Mans> cmp caguide2011.pdf caguide2011a.pdf
caguide2011.pdf caguide2011a.pdf differ: byte 737661, line 2547
chris@server:~/Documents/Le Mans>
chris@server:~/Documents/Le Mans> md5sum caguide2011.pdf
72dc1fbc6b5bbd8d1813f2ccb669985c caguide2011.pdf
chris@server:~/Documents/Le Mans> md5sum caguide2011a.pdf
79531744fae9309e990d7335193e5b87 caguide2011a.pdf
chris@server:~/Documents/Le Mans>
chris@server:~/Documents/Le Mans>