This script freezes my game and I don't know why. Please help?

Pretty sure its got to do with the while loop on line 45, no idea what you are trying to do in this loop but its wrong.

For instance, you use i as your timer number but also reuse it in a for loop on line 47 (for i,v) so the timer version of i never gets subtracted from because you only subtract within this loop. Rename one of the i's.

Also line 38, :disconnect is deprecated but :Disconnect() isn't so if you wanna change that.

Alright, so the problem still occurs, and here is the revised code:

function doSpecialRound(buildTime, voteTime, intermissionTime)
    throw("notification","This round will be different!")
    wait(11)
    throw("notification","This round you will have to guess what the player is building")   
    setStatus("Choosing builder...")
    wait(3)
    player = get_Child(game.Players,math.random(0,#game.Players:GetChildren()))
    if player.Character and player.Character.HumanoidRootPart then
        player.Character:MoveTo(workspace.Teleports.LobbyBase.base.Position)
    end
    -- Give tools
    for i,v in pairs(game.ServerStorage.StamperTools:GetChildren()) do
        tool = v:Clone()
        tool.Parent = player.Backpack
    end
    ncs = script.Resources.NoChatScript:Clone()
    ncs.Parent = player.Backpack
    ncs.Disabled = false
    workspace.MakeChat:FireAllClients("The bonus round has started! Chat what you think the builder is making!")
    timer = 90
    category = tostring(cat[ch])
    for i,v in pairs(game.Players:GetChildren()) do
        v.PlayerGui.main.Frame.Category.Text = "Mystery"
    end
    player.PlayerGui.main.Frame.Category.Text = category
    -- Chat hook
    setStatus("Mystery round...")
    for i,v in pairs(game.Players:GetChildren()) do
        pcall(function()
        v.Chatted:connect(function(msg)
            if string.lower(msg) == string.lower(category) then
                throw("msg",v.Name .. " has guessed the theme!")
                workspace.MakeChat("The theme was " .. category)
                game.PointsService:AwardPoints(v.UserId,100)
                v.leaderstats.Wins.Value = v.leaderstats.Wins.Value+1
                for i,v in pairs(game.Players:GetChildren()) do
                pcall(function()
                v.Chatted:disconnect() -- Deprecated, but options are limited
                end)
                end
            end
        end)
        end)
    end
    while timer > -1 do
        for _,v in pairs(game.Players:GetChildren()) do
            pcall(function()
            v.PlayerGui.main.Frame.Time = timer
            timer=timer-1
            wait(1)
            end)
        end
    end
end