I have a few bugs,when i try to ad lights to a large sign the program becomes unresponsive

Bug 2 The preview render will sometimes render just the background color

Bug 3 when useing the preview render my system becomes unresponsive or takes a very long time render a small section 5 minutes or better

Bug 4 trying to pose the V4 to V3 model is very hard and mostly unresponsive

Theses bugs are using one model set Apartment 39 plus V4 to V3 model

System  

Windows Xp Pro Sp2 all updates
Nvida 7800GS Video Card  93.71 Drivers
2 LCD Monitors
3.40 P4 W/Hyperthreading
2 Gigs of Ram

Jack Of All Trades Master Of None