Graphical floor glitch in Docks

There are green textured patches of what looks like grass appearing on the Docks. The flicker while moving and change shape depending on my camera angle and zoom. sometimes disappearing.




Operating System: Windows 7 Home Premium 64-bit (6.1, Build 7601) Service Pack 1 (7601.win7sp1_gdr.130318-1533)
System Manufacturer: eMachines
System Model: eME640G
BIOS: InsydeH2O Version V2.04
Processor: AMD Athlon(tm) II P340 Dual-Core Processor (2 CPUs), ~2.2GHz
Memory: 10240MB RAM
Available OS Memory: 10234MB RAM
Page File: 7912MB used, 12555MB available
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: Using System DPI
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
DxDiag Version: 6.01.7601.17514 64bit Unicode

Card name: ATI Mobility Radeon HD 5400 Series
Manufacturer: Advanced Micro Devices, Inc.
Chip type: AMD Radeon Graphics Processor (0x68E0)
DAC type: Internal DAC(400MHz)
Device Key: Enum\PCI\VEN_1002&DEV_68E0&SUBSYS_036E1025&REV_00
Display Memory: 1264 MB
Dedicated Memory: 498 MB
Shared Memory: 765 MB
Current Mode: 1366 x 768 (32 bit) (60Hz)
Monitor Name: Generic PnP Monitor
Monitor Model: unknown
Monitor Id: CMO1599
Native Mode: 1366 x 768(p) (60.001Hz)
Output Type: Internal

More info, these are the grass/moss patches normally on the floor, they glitch when they overlap with the cart tracks