I have a PDF embedded in an email. It displays properly on my iMac and on my iPhone, but the iPad does not display it - it only shows the question mark icon, indicating that it doesn't know how to handle the PDF.
I am having the same problem. I work in an architectural firm and the drawings I send to the iPad in pdf format download and then show a blue square with a question mark and won't open. The same pdf opens fine on my iPhone and in Mac Mail. I was looking foward to being able to see drawings on the larger screen.
Try some different PDF from different locations. I have not had this issue. So could be something in your PDFs that the iPad does not like. Possibly the type of PDF. Or a type of media in the PDF.
I'm having the same problem myself, I've tried many different .pdf's from multiple applications and there doesn't seem to be a consistent error except that it's fine with any multi-page .pdf just not single page ones?
I experienced the same issue with the PDF showing as a blue box with a question mark on my iPad, and displaying properly on my iPhone and MacBook. I went in to the Apple Genius bar and what they discovered was that the issue was related to Comcast (that was the e-mail account that was experiencing the issue). I forwarded the message containing the PDF to my gmail account and the PDF's displayed properly on the iPad. Not ideal to have to view PDF's on my non-primary email account, but I am sure Comcast will fix the issue soon:-)
Just spent 30 mins with Apple Support by phone, and the solution is an easy one... do a HARD RESTART.
Hold down both the home and power buttons simultaneously (don't let go), the red slide to power off box will come up, ignore this and keep those buttons held down. The screen will go black and then the white Apple logo will appear, as soon as it does let go of the home and power buttons... the little blue boxes will now be banished and inline .pdf's work just fine!
Same issue here, on BOTH my 3GS iPhone (iOS4) and my iPad - although with a small twist. I can only see the first page of multiple page pdfs. The first page appears inline, with no opportunity to open it further.