I opened your drawing and it looks fine here. The arcs look smooth and the endpoints are snapped together, so I'm not sure what's causing this on your end?
One thing you could check would be your WHIPARC variable. Try changing the setting to "0" or "1" and then do a REGEN and see if that helps.
Kate did you draw this or was it imported into AutoCAD? Honestly it looks like imported line work to me. The points not meeting at the top of the flower seem like the give away to me. Can you share the file for us to look st in detail?
Looks fine on my computer. What are your computer specifications? Graphics card? Driver? Are you using hardware acceleration (GRAPHICSCONFIG)? Did you try FACETRES?