Some of you may have run into the following problem: you have been accepted to an IEEE conference but your paper cannot be published on IEEE Xplore because it does not fulfill the requirements for publication on this website.
You can check whether your paper fulfills these requirements by uploading it on the IEEE PDF eXpress Plus webpage (you need a login usually provided by the conference you registered to). Then you get a report stating what you need to change to make your paper compatible, if it is not.
IEEE has some guidelines to help you solve compatibility issues. However, they were not useful in my case. My paper did not fulfill the requirements because of two main reasons: bookmarks were found in the pdf file of my article and some fonts were not embedded in the pdf file.
If you ever have the same problems, here are some solutions I found.
[Edit: The solutions below apply when you create a pdf file through latex + dvips + ps2pdf. Those of you who use pdflatex can try Sébastien's suggestion in the comments. Thanks Sébastien for sharing this!]
For the bookmark issues, you need to load the hyperref package with the option “bookmarks=false”. This means that you need to write this in the preamble of your latex file:
\usepackage[bookmarks=false]{hyperref}
For the font issue, the problem seems to arise when converting the ps file to pdf. On this website, a solution is given by running gswin32 on your ps file with some options:
gswin32c.exe -dSAFER -dNOPLATFONTS -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sPAPERSIZE=letter -dCompatibilityLevel=1.4 -dPDFSETTINGS=/printer -dCompatibilityLevel=1.4 -dMaxSubsetPct=100 -dSubsetFonts=true -dEmbedAllFonts=true -sOutputFile=mypaper.pdf -f mypaper.ps
Where you replace mypaper.ps by the name of your ps file.
This is not very simple because you have to invoke the command line. Most latex editors let you customize the ps to pdf process. Here is how I have done it for winedt:
You have to change the execution mode for conversion from ps to pdf. It is in the menu “options”:

There you have to change the field named “switches” with the following line:
-dSAFER -dNOPLATFONTS -dNOPAUSE -dBATCH -sDEVICE=pdfwrite -sPAPERSIZE=letter -dCompatibilityLevel=1.4 -dPDFSETTINGS=/printer -dCompatibilityLevel=1.4 -dMaxSubsetPct=100 -dSubsetFonts=true -dEmbedAllFonts=true

That’s it!
Try now to reupload your new pdf file to the IEEE PDF eXpress website. You should now have got rid of both bookmark and font issues.