Photoshop :: CS4 Trial Bugs - Eraser &...

I recently downloaded the Photoshop CS4 Extended Trial and installed it on my computer...I am noticing some bugs and im not really sure if its just a bug in the trial version which will be fixed when i buy the program or if there was an error with the install... I dont have screenshots at the moment since im not on the computer having the issue but i can get them if needed... First lets start with the eraser tool...When i set the eraser tool as a size of say about 10px it works fine...However, if i zoom in on the image above its nautral size i start to lose the eraser...When i say lose the eraser i mean you can no longer seen the round area which will be erased..When you zoom in part of the circle disappears...It will still erase and area of the set size but its sort of hard to do erasing on detailed images when you cant see the whole eraser.... More bugs with the eraser....If i set the eraser to a larger size, say 30px or more, i right off the bat start seeing less of the eraser area....It will go from a whole circle down to something like a half moon with only half the circle being displayed... This may be a little hard to understand so if need be i will get some screenshots of what im talking about later....  I am also having a problem with the text...For starters, i cant scroll through the text...When i enter text and highlight it and highlight the fonts i would expect to be able to scroll through the fonts while watching the actual text change on thet screen....I am unable to do that, i highlight the text and the fonts and CS4 will let me scroll maybe 4-5 fonts and then it just stops and wont scroll anymore... Another issue im having with the font is the size....Whenever i enter text it is extremely small...Even if im working with a 200px x 200px image if i set my font at say 75px its tiny, tiny enough to where i cant even see it to highlight it....There appears to be something wrong with the sizing of the text...Just to get text to show up normally, at a readable size, i have to set the font size to 800px+ and this is on images which are only like 600px wide and 300px tall...Usually a font of 800px would fill up this image but when i do it the 800px font shows up like a 36px font... Like i said if this is all to hard to understand i can get some screen shots later on...I wanna make sure this is something which can be fixed before i go ahead and drop 700+ on the program...