title: when I start Desktop Rstudio every time, I get an error message as:rstudio error yaml.load readlin con errorlevel errorlevel
body: <p>after I login the Desktop Rstudio, the following message will appear:</p>
  
  <pre><code>Error in yaml.load(readLines(con), error.label = error.label, ...) : 
    object 'C_unserialize_from_yaml' not found
  Error in yaml.load(readLines(con), error.label = error.label, ...) : 
    object 'C_unserialize_from_yaml' not found
  Error in yaml.load(readLines(con), error.label = error.label, ...) : 
    object 'C_unserialize_from_yaml' not found
  Error in yaml.load(readLines(con), error.label = error.label, ...) : 
    object 'C_unserialize_from_yaml' not found
  Error in yaml.load(readLines(con), error.label = error.label, ...) : 
    object 'C_unserialize_from_yaml' not found
  and I try to reinstall R and Rstudio with the newest program,it still appear error again.
  when I start R program ,it can work with no error. Only Rstudio, and I try to rename the directory"C:\Users\Administrator\AppData\Local\RStudio-Desktop" in another name, Let it create when Rstudio launch,the error message again. 
  And I can't knit some Rmd file working normal, it will appear following error:
  Error in yaml::yaml.load(string, ...) : 
    找不到对象'C_unserialize_from_yaml'
  Calls: &lt;Anonymous&gt; ... parse_yaml_front_matter -&gt; yaml_load_utf8 -&gt; &lt;Anonymous&gt;
  停止执行
  </code></pre>
  
  <p>Who can help me to slove the problem.Thanks very much.</p>