I have the same issue. Disabling Hardware Accelerated Rendering (GPU) works for me too.
Application paint.net v4.0 (Final 4.0.5288.36565)
Build Date 24 czerwca 2014
Renderowanie przyspieszane sprzętowo (GPU) False
Animacje True
Język pl-PL
OS Windows 8.1 (6.3.9600.0)
.NET Runtime 4.0.30319.34014
Physical Memory 3 523 MB
CPU AMD A6-5200 APU with Radeon(TM) HD Graphics
Architecture x64 (64-bit)
Process Mode 64-bit
Speed ~1996 MHz
Cores / Threads 4
Features DEP, SSE, SSE2, SSE3, SSSE3, SSE4_1, SSE4_2, XSAVE
Video Card AMD Radeon HD 8400
Dedicated Video RAM 1 513 MB
Dedicated System RAM 0 MB
Shared System RAM 1 536 MB
Vendor ID 0x1002
Device ID 0x9830
Subsystem ID 0xFA341179
Revision 0
LUID 0x0000C054
Flags None
Outputs 1
Video Card Microsoft Basic Render Driver
Dedicated Video RAM 0 MB
Dedicated System RAM 0 MB
Shared System RAM 256 MB
Vendor ID 0x1414
Device ID 0x008C
Subsystem ID 0x00000000
Revision 0
LUID 0x0000C60F
Flags Software
Outputs 0