I have a Panasonic TX-L22X20B and the text appears distorted (very disturbing to read). I have a Radeon HD 5450 graphics card (which isn't the problem). I have tried various things such as changing brightness, contrast and sharpness which did make things slightly better. However it is still disturbing to look at the screen. I am using a HDMI connection with 1920 x 1080 resolution. When I connect a PC cable it seems just fine but the resolution is lower and the display is large.
you might want to explain the issue in another way. i'm not quite sure what you are trying to say.
a photo of the issue might also help.
i took a look at your tv TX-L22X20B and it is only 1366x768 resolution at a 22 inch size. click >HERE< to see the specifications. what this means is that your tv can NOT display 1920x1080 but only 1366x768 resolution. everything will be rather large on screen as you are using a fairly decent sized screen but only a lower resolution. honestly it will look alot like how windows 98 and xp used to look on screens of that era.
now why does your tv list 1080 support but doesnt work with it? my guess would be that it downgrades the 1080p signal coming in to fit on its 1366x768 display. of course this causes quality loss. i'm not sure as your description is vague but it sounds like if you connect via hdmi it appears fine but text is hard to read and distorted but when you connect via a different method (not sure what you mean by pc cable) you get everything looking really large. my guess would be that when hooked up to the pc it recognizes that the monitor is only 1366x768 and sets the windows resolution to that but when you have it via hdmi the tv is downsizing the signal to fit on your display which is what causes distortion.
in short: you need to run the screen at 1366x768 only. you always need to run at the native resolution.
if you want 1080p you need to go out and buy a 1920x1080 monitor or television.