Happens on all of my machines. Sometimes mouse clicks do not register, other times it will repeatedly click by itself until I click to stop it. Happens on all of my machines which are using Ubuntu 13.10 and Ubuntu 14.04 with the latest open source drivers. Raw input is enabled in TF2.

Processor Information:
Vendor: AuthenticAMD
CPU Family: 0x10
CPU Model: 0xa
CPU Stepping: 0x0
CPU Type: 0x0
Speed: 2800 Mhz
6 logical processors
6 physical processors
HyperThreading: Unsupported
FCMOV: Supported
SSE2: Supported
SSE3: Supported
SSSE3: Unsupported
SSE4a: Supported
SSE41: Unsupported
SSE42: Unsupported

Network Information:
Network Speed:

Operating System Version:
Zorin OS 8 (64 bit)
Kernel Name: Linux
Kernel Version: 3.13.0-031300-generic
X Server Vendor: The X.Org Foundation
X Server Release: 11405000
X Window Manager: Compiz
Steam Runtime Version: steam-runtime-release_2013-10-23

Video Card:
Driver: X.Org Gallium 0.4 on AMD BARTS

Driver Version:  3.0 Mesa 10.1.0-devel (git-f7c118f saucy-oibaf-ppa)
OpenGL Version: 3.0
Desktop Color Depth: 24 bits per pixel
Monitor Refresh Rate: 59 Hz
VendorID:  0x1002
DeviceID:  0x6739
Number of Monitors:  1
Number of Logical Video Cards:  1
Primary Display Resolution:  1920 x 1080
Desktop Resolution: 1920 x 1080
Primary Display Size: 21.38" x 12.01"  (24.49" diag)
                                        54.3cm x 30.5cm  (62.2cm diag)
Primary VRAM Not Detected

Sound card:
Audio device: VIA VT1708S

Memory:
RAM: 7983 Mb

Miscellaneous:
UI Language: English
LANG: en_US.UTF-8
Microphone: Not set
Total Hard Disk Space Available: 821116 Mb
Largest Free Hard Disk Block: 165235 Mb

Installed software:

Recent Failure Reports: