When I use TeXnicCenter to open a PDF outputs file (using Adobe Reader and DDE commands), it will hang if I close Adobe Reader before the DDE command to open the file are sent.
When TXC opens Adobe Reader, the PDF file is not open immediately. Adobe Reader opens the file when TXC actually sends the DDF command to do so, after a brief delay. If Adobe Reader is closed before the DDE command is sent, TXC will hang.
Even while hung, if I open Adobe Reader manually again, TeXnicCenter will successfully send the DDE command and continue working normally.