A lot of people have been having Cydia crashes lately, most often while attempting a package upgrade that fails. The symptom is that Cydia will crash almost immediately after opening.
I had that problem and traced the issue to corrupt files in /var/lib/dpkg/updates/. Removing all files in that directory solved the problem for me and for several other people on the MacRumors iPhone forum. There have been people whom this didn't work for as well, but it's worked for more than it's failed, and it won't hurt anything to try if you're suffering Cydia crashes.
Here are a few methods for deleting those files.
Open MobileTerminal on the phone and type "rm /var/lib/dpkg/updates/*" (without quotes) and hit enter.
SSH into the phone and type "rm /var/lib/dpkg/updates/*" (without quotes) and hit enter.
Use the apps iFile or Discover from Cydia to browse to /var/lib/dpkg/updates/ and swipe the files then select delete, or in iFile select edit, check all the files, then tap the trash can at the bottom.
If you don't have MobileTerminal, SSH, iFile or Discover installed, you obviously can't install them through Cydia if it is crashing. You may try installing them through Icy, if you have that installed.
I'm sure there are other ways of doing this, but I'm currently unaware of them.
iPhone and Linux