I got the similar problem when using Quartus II 9.1 and
I fixed it by changing the setting of Nios II processor in SOPC Builder.
As shown in attached picture, the memory segment for "Reset Vector" should be the same as that in the property of system library "Program memory (.text)".
Also, I found that memory segment for "Exception Vector" would be put together within segment for .text from the linker script that is automatically generated by Nios II tools. Therefore, I think this memory should be set as the same as "Reset Vector".
You can see this linker script from path:
\software\XXX_syslib\Debug\system_description\generated.x