Using /saveini is unlikely to make any difference. The purpose of /saveini is to make sure that any cached settings are saved immediately for scripts that want to access mirc.ini directly.
mIRC saves files in a two step process. It creates a temporary file first, saves all settings to it, and only if that is successful, with no errors, does it then delete mirc.ini and rename the temporary file to mirc.ini. If there is an error of any kind during the process, it leaves the original mirc.ini untouched. This is the safest way to update files.
I assume that in your case, you are using mIRC on a daily basis, and that you are repeatedly running and closing it, and that it is constantly updating the mirc.ini file. For you to see this error once every few months, under such intensive use, it really does seem more likely that the cause is due to something else, such as low memory, a Windows issue, interference from other applications, and so on.
