Error Messages From xargs

environment is too large for exec: This message means that you have so many environment variables set (or such large values for them) that there is no room within the system-imposed limits on program command-line argument length to invoke any program. I'm sure you did this deliberately. Please try unsetting some environment variables, or exiting the current shell.
can not fit single argument within argument list size limit: You are using the -i option and xargs doesn't have enough space to build a command line because it has read in a really large item and it doesn't fit. You can probably work around this problem with the -s option, but the default size is pretty large. You must be trying pretty hard to break xargs.
cannot fork: See the description of the similar message for find.
<program>: exited with status 255; aborting: When a command run by xargs exits with status 255, xargs is supposed to stop. If this is not what you intended, wrap the program you are trying to invoke in a shell script which doesn't return status 255.
<program>: terminated by signal 99: See the description of the similar message for find.