When the slot name is 'Cache' and the line is 80, then as Mithran notes:
... This problem is most likely caused by either an invalid or blank image file trying to be loaded, or another file with the same name as the image file trying to be loaded in the same directory that is not an image file your Title folder should hold only valid images and only one of each by any given name (Bitmap class will load the first file with the name, regardless of the extension)...
In other words, find out which graphic was trying to be loaded and then go to the corresponding folder in Graphics (like System, Battlers, Characters, etc...). Make sure there is only one file in the folder by that name and make sure it is a valid image file.
As GubiD notes, this error may also occur when a script tries to create a Bitmap with a width or height of less than 1. This is most likely a logic error on the part of the scripter and he or she will need to be alerted. However, if there is a configuration section that allows you to choose the width or height of something (like a window) then it could be a user error as well. Make sure that any time there are values like that, they are within appropriate parameters. (This may or may not be a problem depending on the script - I know for some of my scripts where I let the width or height of something be configurable, I will have a value of -1 be an indication to have the window's size be automatically sized depending on other factors, such as the size of other windows at the time or the resolution of the screen. So read the instructions, but that may be the problem.)
Similarly, this error can occur if the width and height are too large, and that may occur where a script generates the size of a Bitmap depending on how many items are to be listed in the window. That can happen if you have, for instance, lots of different stacks of items in Scene_Item. Yanfly wrote a fix for that in her Core Fixes, though it is not a perfect fix as it will cut off the offending items in the list. As far as I know, there is no perfect general fix for it, but a scripter might be able to whip something up for you by, for instance, swapping bitmaps. The other thing you could do is reduce the number of items that will appear in the list at any given time.