SteamStartup failed while trying to load Garry's Mod

Hello, and thank you for trying to help me with my rather big problem. I have already renamed a folder to garrysmodold, and I do not feel like doing this again. But if I have to, I will. Also, I do not have TortuiseSVN.

Situation: While trying to launch Garry’s Mod, the game almost loads when a window pops up and says this:

SteamStartup() failed: SteamStartup(0xf,0x0012E584) failed with error 1: failed to take master pipe connection lock

Computer:
OS Name Microsoft® Windows Vista™ Home Premium
Version 6.0.6002 Service Pack 2 Build 6002
System Model Inspiron 531
System Type X86-based PC
Processor AMD Athlon™ 64 X2 Dual Core Processor 4400+, 2310 Mhz, 2 Core(s), 2 Logical Processor(s)
BIOS Version/Date Dell Inc. 1.0.13, 2/9/2009
SMBIOS Version 2.5

Addons: ADVSleepnWakeSTool
adv-turret
Age of Chivalry
Bail Out (Seems to be the problem cause every time I try to use it, it won’t load [which is to say: no bail out of car])
Bank Robbers
Billy Mays
Bodygroup_STool
Catmull-Rom Cameras
cheesylard
counter-strike (I do not own this game)
DaftPunkPlayerModels
day-of-defeat (I do not own this game)
default_sent_pack
derma
enginemod
Enviorment Stools
gm_atomic
gm_bigcity
gm_XhS_construct
gm_xhs_revolution
Greenscreen Materials
HAAX_Swep
hl2_ep2 (I do not own this game)
KCGEORGE’s Sniper Rifle Pack 2
kermite
Left4Dead
Left 4 Dead (I do not own this game)
Left 4 Dead 2 (I do not own this game)
melongun
Metropolice NPC’s
mount2
My npc’s
mymelon
No collide world
NPC_Control2
npcgun
Nuke Pack 4
Officer
pcmod2
pctuning
Phoenix_Storm
Playermodel Pack
portal
Prop Resizer v2
RagMorph
SCars
shuriken
Stool - Explosive Entities
tf2 (I do not own this game)
TOOL_stacker_adv
Turret Vehicles
V
VehicleUpgrade
Waterizer
Weapon Seats
WeightSTool
wire (addon, not SVN)
wire model pack 1 (addon, not SVN)
zeno_clash (I do not own this game)

Is that too indepth?

Restart steam.
Edit: So many addons…
Must…delete…

Yay for AMD.
AMD athlon™ 64 X2 Dual Core Processor 5000+ 2.59GHz

Yeah, I’m kinda and idiot for not thinking that, cause soon as I did, it was working. facepalm
I have so many addons because my lack of Steam games (Currently own: Portal, Half Life 2: Deathmatch, Half Life 2: Lost Coast) makes be bored so I have all these addons to try to make up for it. The only reason that I listed them was becuase of the forum rules.

I only use hl2 and portal props from source games, so that is no excuse.

That isnt caused by addons. its caused by steam, It randomly happens and you should be fine to install the addons you had(if you want extreme slow loading time)